From Science News: “Machine learning helped demystify a California earthquake swarm”

From Science News

June 18, 2020
Carolyn Gramling

New data show the spread of the tiny quakes through complex fault networks over time.

By training computers to identify tiny earthquake signals recorded by seismographs, scientists found that circulating groundwater probably triggered a four-year-long earthquake swarm in Southern California.Credit: Furchin/E+/Getty Images

Circulating groundwater triggered a four-year-long swarm of tiny earthquakes that rumbled beneath the Southern California town of Cahuilla, researchers report in the June 19 Science. By training computers to recognize such faint rumbles, the scientists were able not only to identify the probable culprit behind the quakes, but also to track how such mysterious swarms can spread through complex fault networks in space and time.

Seismic signals are constantly being recorded in tectonically active Southern California, says seismologist Zachary Ross of Caltech. Using that rich database, Ross and colleagues have been training computers to distinguish the telltale ground movements of minute earthquakes from other things that gently shake the ground, such as construction reverberations or distant rumbles of the ocean (SN: 4/18/19). The millions of tiny quakes revealed by this machine learning technique, he says, can be used to create high-resolution, 3-D images of what lies beneath the ground’s surface in a particular region.

In 2017, the researchers noted an uptick in tiny quake activity in the Cahuilla region that had, at that point, been going on for about a year. Most of the quakes were far too small to be felt but were detectable by the sensors. Over the next few years, the team used their computer algorithm to identify 22,000 such quakes from early 2016 to late 2019, ranging in magnitude from 0.7 to 4.4.

Such a cluster of small quakes, with no standout, large mainshock, is called a swarm. “Swarms are different from a standard mainshock-aftershock sequence,” which are typically linked to the transfer of stress from fault to fault in the subsurface, Ross says. The leading candidates for swarm triggering come down to groundwater circulation or a kind of slow slippage on an active fault, known as fault creep.

“Swarms have been somewhat enigmatic for quite a while,” says David Shelly, a U.S. Geological Survey geophysicist based in Golden, Colo., who was not connected with the study. They are particularly common in volcanic and hydrothermal areas, he says, “and so sometimes, it’s a bit harder to interpret the ones that aren’t in those types of areas,” like the Cahuilla swarm (SN: 5/14/20).

“This one is particularly cool, because it’s [a] rare, slow-motion swarm,” Shelly adds. “Most might last a few days, weeks or months. This one lasted four years. Having it spread out in time like that gives a little more opportunity to examine some of the nuances of what’s going on.”

Data from the Cahuilla swarm, which is winding down but “not quite over,” Ross says, revealed not only the complex network of faults beneath the surface, but also the evolution of the fault zone over time. “You can see that the sequence [of earthquakes] originated from a region that’s only on the order of tens of meters wide,” Ross says. But over the next four years, he adds, that region grew, creating an expanding front of earthquake epicenters that spread out at a rate of about 5 meters per day, until it became about 30 times the size of the original zone.

That diffusive spread, Ross says, suggests that moving groundwater is triggering the swarm. Although the team didn’t directly observe fluids moving underground, the scientists speculate that beneath the fault zone lies a reservoir of groundwater that previously had been sealed off from the zone. At some point, that seal broke, and the groundwater was able to seep into one of the faults, triggering the first quakes. From there, it moved through the fault system over the next few years, triggering more quakes in its wake. Eventually, the seeping groundwater probably ran up against an impermeable barrier, which is bringing the swarm to a gradual halt.

Being able to identify what causes such mysterious events is extremely important when it comes to communicating with people about earthquake hazards, Ross says. “Typically, we have very limited explanations that we can provide to the public on what’s happening,” he says. “It gives us something that we can explain in concrete terms.”

And this discovery, he adds, “gives me a lot of confidence” to continue to apply this technique, such as on the last 40 years of amassed seismic data in Southern California, which likely contains many more previously undetected swarms.

The study highlights how seismologists are increasingly acknowledging the importance of fluids in the crust, Shelly says. And, he adds, it emphasizes how having so many tiny quakes can illuminate the hidden world of the subsurface. “It’s kind of like having a special telescope to look down into the crust,” he adds. Combining this wealth of seismic data with machine learning is “the future of earthquake analysis.”

______________________________________________

Earthquake Alert

Earthquake Alert

Earthquake Network projectEarthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

Get the app in the Google Play store.

Smartphone network spatial distribution (green and red dots) on December 4, 2015

Meet The Quake-Catcher Network

Quake-Catcher Network

The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

Below, the QCN Quake Catcher Network map

ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

Watch a video describing how ShakeAlert works in English or Spanish.

The primary project partners include:

United States Geological Survey
California Governor’s Office of Emergency Services (CalOES)
California Geological Survey
California Institute of Technology
University of California Berkeley
University of Washington
University of Oregon
Gordon and Betty Moore Foundation

The Earthquake Threat

Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

Part of the Solution

Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

System Goal

The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

Current Status

The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

Authorities

The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

For More Information

Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
rdegroot@usgs.gov
626-583-7225

Learn more about EEW Research

ShakeAlert Fact Sheet

ShakeAlert Implementation Plan

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

From temblor: “Magnitude-6.5 earthquake rattles Nevada and California”

From temblor

May 15, 2020
Alka Tripathy-Lang, PhD

A shallow earthquake struck near the California-Nevada border in the early morning hours on May 15, 2020, waking people as far away as the Bay Area and Las Vegas.

A magnitude-6.5 quake struck a remote part of Nevada today (May 15, 2020), but was felt in the San Francisco Bay area, Bakersfield, and Las Vegas. Based on its aftershocks and focal mechanism, the event probably struck on an unnamed left-lateral fault. Credit: Temblor

On May 15, 2020, at 4:03 a.m. local time, the desert area west of Tonopah, Nev., was rattled awake by a widely felt magnitude-6.5 earthquake. Nucleating at a depth of 1.7 miles (2.8 kilometers), this shallow temblor occurred on a nearly vertical fault surface where no matter which side of the fault you’re on, the other side moved to the left. Called a left-lateral strike-slip fault, it is similar to the fault that ruptured during the magnitude-6.4 Ridgecrest foreshock that struck approximately 170 miles (270 kilometers) to the south less than a year ago.

Damage appeared to be minimal, with the Nevada Department of Transportation reporting minor pavement damage to a half-mile section of U.S. Highway 95.

Earthquakes east of the Sierra Nevada

As the Pacific Plate moves northwest relative to North America, much of that motion occurs on the famed San Andreas Fault. However, a significant component of the movement between these two tectonic plates, almost 20-25 percent of the total motion, shows up several hundred miles to the east, in the Walker Lane Belt, says Ian Pierce, a postdoctoral researcher at Oxford University who studies active faults. The Walker Lane Belt runs roughly parallel to the California-Nevada border, east of the Sierra Nevada. Like the notorious San Andreas, Walker Lane is a right-lateral fault zone, meaning whichever side you are on, the other side moves to the right.

Spanning 500 miles (800 kilometers) between near Ridgecrest, Calif., at its southern extent into the northern Sierra Nevada, the Walker Lane Belt comprises many smaller zones of right-lateral faulting that are linked by small left-lateral faults, says Pierce. “It looks like this earthquake was one of those left-lateral faults rupturing,” he says. “As far as the tectonic setting,” he continues, “it’s basically the same as Ridgecrest last year.”

Similarities to Ridgecrest

On July 4, 2019, a magnitude-6.4 foreshock rattled Ridgecrest’s residents, but that was just the opening act to the magnitude-7.1 mainshock, which occurred 34 hours later. Pierce compares the Tonopah earthquake with the Ridgecrest foreshock, and points out that aside from their similar magnitudes, “they both occurred on left-lateral faults with small surface ruptures on fairly short—maybe 20-kilometer—fault[s]

Map of the southern section of the Walker Lane Belt around surrounding regions showing the the past 30 days of earthquake activity. The three stars indicate important quakes—the July 2019 Ridgecrest magnitude-6.4 foreshock, the July 2019 Ridgecrest magnitude-7.1 mainshock, and the Tonopah magnitude-6.5 event of May 15, 2020. Stars are scaled to correspond with magnitude. Credit: Temblor

However, Pierce says, although Ridgecrest started with a big quake and was followed by an even larger one the next day, “we probably won’t have a magnitude-7.1 tomorrow.”

Aftershock forecasts

The U.S. Geological Survey (USGS) issues aftershock forecasts, which can be found here. Over the course of the next week, the chance of an aftershock with magnitude-7.0 or higher is 1 percent, indicating that it’s certainly possible, but with very low probability. On the other hand, the chance of a magnitude-3.0 aftershock or higher is greater than 99 percent. As of this writing, at least 12 aftershocks greater than magnitude-4.0 have been reported, including magnitude-4.9 and magnitude-5.1 shocks that occurred less than an hour after the mainshock.

“People don’t think of Nevada as being very active, but it really is,” says Kathleen Hodgkinson, a geophysicist at UNAVCO.

Felt on the other side of the mountains

As of this writing, more than 21,000 people have reported feeling (or not feeling) the event, according to the USGS “Did you Feel It?” citizen science initiative. People felt the distinctive shaking associated with earthquakes in Las Vegas, about 170 miles (280 kilometers) to the southeast, all the way to the California Bay Area, about 280 miles (450 kilometers) west. Austin Elliot, a research geologist at the USGS Earthquake Science Center in the Bay Area, described waking up to “the seemingly ceaseless thumping of the closet doors” on twitter. He also pointed out that “building height amplified the otherwise maybe imperceptible ground motions,” referencing the fact that the higher up you are, the more likely you are to feel the swaying as seismic waves pass by.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Earthquake Alert

Earthquake Alert

Earthquake Network project

Earthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

Get the app in the Google Play store.

Smartphone network spatial distribution (green and red dots) on December 4, 2015

Meet The Quake-Catcher Network

Quake-Catcher Network

The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

Below, the QCN Quake Catcher Network map

ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

Watch a video describing how ShakeAlert works in English or Spanish.

The primary project partners include:

United States Geological Survey
California Governor’s Office of Emergency Services (CalOES)
California Geological Survey
California Institute of Technology
University of California Berkeley
University of Washington
University of Oregon
Gordon and Betty Moore Foundation

The Earthquake Threat

Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

Part of the Solution

Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

System Goal

The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

Current Status

The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

Authorities

The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

For More Information

Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
rdegroot@usgs.gov
626-583-7225

Learn more about EEW Research

ShakeAlert Fact Sheet

ShakeAlert Implementation Plan

From Stanford University: “Stanford researchers create seismic stress map of North America”

From Stanford University

April 23, 2020

Media Contacts

Danielle Torrent Tucker
School of Earth, Energy & Environmental Sciences
(650) 497-9541
dttucker@stanford.edu

Mark Zoback,
School of Earth, Energy & Environmental Sciences
(650) 725-9295
zoback@stanford.edu

Jens-Erik Lund Snee,
School of Earth, Energy & Environmental Sciences:
(720) 289-8972
jlundsnee@usgs.gov

How do mountains form? What forces are needed to carve out a basin? Why does the Earth tremble and quake?

New research has direct applications for understanding and mitigating problems associated with induced seismicity – human-caused earthquakes – from unconventional oil and gas recovery. (Image credit: Alexlky/iStock)

Earth scientists pursue these fundamental questions to gain a better understanding of our planet’s deep past and present workings. Their discoveries also help us plan for the future by preparing us for earthquakes, determining where to drill for oil and gas, and more. Now, in a new, expanded map of the tectonic stresses acting on North America, Stanford researchers present the most comprehensive view yet of the forces at play beneath the Earth’s surface.

The findings, published in Nature Communications on April 23, have implications for understanding and mitigating problems associated with induced seismicity – human-caused earthquakes – from unconventional oil and gas recovery, especially in Oklahoma, Texas and other areas targeted for energy exploration. But they also pose a whole new set of questions that the researchers hope will stimulate a wide range of modeling studies.

“Understanding the forces in the Earth’s crust is fundamental science,” said study co-author Mark Zoback, the Benjamin M. Page Professor of Geophysics in Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “In some cases, it has immediate application, in others, it may be applied decades later to practical questions that do not exist today.”

First continental synthesis of data

The new research provides the first quantitative synthesis of faulting across the entire continent, as well as hundreds of measurements of compressive stress directions – the direction from which the greatest pressure occurs in the Earth’s crust. The map was produced by compiling new and previously published measurements from boreholes as well as inferences about kinds or “styles” of faults based on earthquakes that have occurred in the past.

Credit: Jens-Erik Lund Snee and Mark Zoback

The three possible styles of faulting include extensional, or normal faulting, in which the crust extends horizontally; strike-slip faulting, in which the Earth slides past itself, like in the San Andreas fault; and reverse, or thrust, faulting in which the Earth moves over itself. Each one causes very different shaking from a hazard point of view.

“In our hazards maps right now, in most places, we don’t have direct evidence of what kind of earthquake mechanisms could occur,” said Jack Baker, a professor of civil and environmental engineering who was not involved with the study. “It’s exciting that we have switched from this blind assumption of anything is possible to having some location-specific inferences about what types of earthquakes we might expect.”

Zooming in

In addition to presenting a continent-level view of the processes governing the North American plate, the data – which incorporates nearly 2,000 stress orientations, 300 of which are new to this study – offer regional clues about the behavior of the subsurface.

“If you know an orientation of any fault and the state of stress nearby, you know how likely it is to fail and whether you should be concerned about it in both naturally-triggered and industry-triggered earthquake scenarios,” said lead author Jens-Erik Lund Snee, PhD ’20, now a postdoctoral fellow with the United States Geological Survey (USGS) in Lakewood, Colorado. “We’ve detailed a few places where previously published geodynamic models agree very well with the new data, and others where the models don’t agree well at all.”

In the Eastern U.S., for example, the style of faulting revealed by the study is exactly the opposite of what would be expected as the surface slowly “rebounds” following the melting of the ice sheets that covered most of Canada and the northern U.S. some 20,000 years ago, according to Lund Snee. The discovery that the rebound stresses are much less than those already stored in the crust from plate tectonics will advance scientists’ understanding of the earthquake potential in that area.

In the Western U.S., the researchers were surprised to see changes in stress types and orientations over short distances, with major rotations occurring over only tens of miles – a feature that current models of Earth dynamics do not reveal.

“It’s just much clearer now how stress can systematically vary on the scale of a sedimentary basin in some areas,” Zoback said. “We see things we’ve never seen before that require geologic explanation. This will teach us new things about how the Earth works.”

See the full article here .

five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

Stanford University campus. No image credit

Stanford University

Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

From Rice University: Women in STEM-“Fed grant backs Rice earthquake research” Geologist Melodie French

From Rice University

January 31, 2020

Jeff Falk
713-348-6775
jfalk@rice.edu

Mike Williams
713-348-6728
mikewilliams@rice.edu

Geologist Melodie French wins National Science Foundation CAREER Award.

Rice University geologist Melodie French has earned a National Science Foundation CAREER Award to support her investigation of the tectonic roots of earthquakes and tsunamis. Photo by Jeff Fitlow.

The tectonic plates of the world were mapped in 1996, USGS.

Rice University geologist Melodie French is crushing it in her quest to understand the physics responsible for earthquakes.

The assistant professor of Earth, environmental and planetary science has earned a prestigious CAREER Award, a five-year National Science Foundation (NSF) grant for $600,000 to support her investigation of the tectonic roots of earthquakes and tsunamis.

CAREER awards support the research and educational development of young scholars likely to become leaders in their fields. The grants, among the most competitive awarded by the NSF, go to fewer than 400 scholars each year across all disciplines.

For French, the award gives her Rice lab the opportunity to study rocks exhumed from subduction zones at plate boundaries that are often the source of megathrust earthquakes and tsunamis. Her lab squeezes rock samples to characterize the strength of the rocks deep underground where the plates meet.

“Fundamentally, we hope to learn how the material properties of the rocks themselves control where earthquakes happen, how big one might become, what causes an earthquake to sometimes arrest after only a small amount of slip or what allows some to grow quite large,” French said.

“A lot of geophysics involves putting out instruments to see signals that propagate to the Earth’s surface,” she said. “But we try to understand the properties of the rocks that allow these different phenomena to happen.”

That generally involves putting rocks under extreme stress. “We squish rocks at different temperatures and pressures and at different rates while measuring force and strain in as many dimensions as we can,” French said. “That gives us a full picture of how the rocks deform under different conditions.”

The lab conducts experiments on both exposed surface rocks that were once deep within subduction zones and rock acquired by drilling for core samples.

Rice University geologist Melodie French and graduate student Ben Belzer work with a rock sample. French has been granted a National Science Foundation CAREER Award to study the tectonic roots of earthquakes and tsunamis. Photo by Jeff Fitlow.

I’m working with (Rice Professor) Juli Morgan on a subduction zone off of New Zealand where they drilled through part of the fault zone and brought rock up from about 500 meters deep,” French said. “But many big earthquakes happen much deeper than we could ever drill. So we need to go into the field to find ancient subduction rocks that have somehow managed to come to the surface.”

French is not sure if it will ever be possible to accurately predict earthquakes. “But one thing we can do is create better hazard maps to help us understand what regions should be prepared for quakes,” she said.

French is a native of Maine who earned her bachelor’s degree at Oberlin College, a master’s at the University of Wisconsin-Madison and a Ph.D. at Texas A&M University.

The award, co-funded by the NSF’s Geophysics, Tectonics and Marine Geology and Geophysics programs, will also provide inquiry-based educational opportunities in scientific instrument design and use to K-12 students as well as undergraduate and graduate-level students.

Geologist Melodie French sets up an experiment in her Rice University lab. She has won a National Science Foundation CAREER Award, a prestigious grant given to young scholars likely to become leaders in their fields. (Credit: Jeff Fitlow/Rice University)

See the full article here .

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Stem Education Coalition

In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

From Eos: “Seismic Sensors in Orbit”

From AGU

From Eos

26 December 2019
Timothy I. Melbourne
Diego Melgar
Brendan W. Crowell
Walter M. Szeliga

A continuously telemetered GNSS station located on the Olympic Peninsula of Washington state. Determining the real-time positions of hundreds of stations like this one to accuracies of a few centimeters within a global reference frame opens a new pipeline of analysis tools to monitor and mitigate risk from the seismic and tsunami hazards of the Cascadia Subduction Zone and other fault systems around the globe. Credit: Central Washington University

Imagine it’s 3:00 a.m. along the Pacific Northwest coast—it’s dark outside and most people are asleep indoors rather than alert and going about their day. Suddenly, multiple seismometers along the coast of Washington state are triggered as seismic waves emanate from a seconds-old earthquake. These initial detections are followed rapidly by subsequent triggering of a dozen more instruments spread out both to the north, toward Seattle, and to the south, toward Portland, Ore. Across the region, as the ground begins to shake and windows rattle or objects fall from shelves, many people wake from sleep—while others are slower to sense the potential danger.

Within a few seconds of the seismometers being triggered, computers running long-practiced seismic location and magnitude algorithms estimate the source of the shaking: a magnitude 7.0 earthquake 60 kilometers off the Washington coast at a depth roughly consistent with the Cascadia Subduction Zone (CSZ) interface, along which one tectonic plate scrapes—and occasionally lurches—past another as it descends toward Earth’s interior. The CSZ is a well-studied fault known in the past to have produced both magnitude 9 earthquakes and large tsunamis—the last one in 1700.

Cascadia subduction zone

The initial information provided by seismometers is important in alerting not only scientists but also emergency response personnel and the public to the potentially hazardous seismic activity. But whether these early incoming seismic waves truly represent a magnitude 7 event, whose causative fault ruptured for 15–20 seconds, or whether instead they reflect ongoing fault slip that could last minutes and spread hundreds of kilometers along the fault—representing a magnitude 8 or even 9 earthquake—is very difficult to discern in real time using only local seismometers.

It’s a vital distinction: Although a magnitude 7 quake on the CSZ could certainly cause damage, a magnitude 8 or 9 quake—potentially releasing hundreds of times more energy—would shake a vastly larger region and could produce devastating tsunamis that would inundate long stretches of coastline.

The USGS produced a scenario ShakeMap for a modeled M 9.0 CSZ earthquake for planning purposes. This ShakeMap page provides information about probable shaking levels at different frequencies but is not very useful for site specific estimates nor does it provide much information about potential impacts.

The 1999 24 page Crew Publication, Cascadia Subduction Zone Earthquakes: A Magniude 9 Earthquake Scenario, takes USGS-model ground motions and NOAA tsunami estimates and paints a generalized picture of the likely damages to regional infrastructure. The scenario then identifes challenges that will be faced in responding and recovering from such an event.

In 2007 CREW produced a publication that summarized potential impacts and lessons learned in three tabletop exercises based on the Cascadia earthquake scenario.

Oregon Department of Transportation examined potential damage to bridges during a scenario M8.3 earthquake on the CSZ.

Some communities must evacuate for miles to get out of the potential inundation zone, meaning that every second counts. The ability to characterize earthquake slip and location accurately within a minute or two of a fault rupturing controls how effective early warnings are and could thus mean the difference between life and death for tens of thousands of people living today along the Pacific Northwest coast.

Enter GPS or, more generally, Global Navigation Satellite Systems (GNSS). These systems comprise constellations of Earth-orbiting satellites whose signals are recorded by receivers on the ground and used to determine the receivers’ precise locations through time. GPS is the U.S. system, but several countries, or groups of countries, also operate independent GNSS constellations, including Russia’s GLONASS and the European Union’s Galileo system, among others. Prominently used for navigational purposes, GNSS ground receivers, which in recent years have proliferated by the thousands around the world, now offer useful tools for rapidly and accurately characterizing large earthquakes—supplementing traditional seismic detection networks—as well as many other natural hazards.

An Initial Demonstration

Fig. 1. Examples of GNSS three-dimensional displacement recorded roughly 100 kilometers from the hypocenters of the 2011 magnitude 9.1 Tohoku earthquake in Japan, the 2010 magnitude 8.8 Maule earthquake in Chile, the 2014 magnitude 8.1 Iquique earthquake in Chile, and the 2010 magnitude 7.2 El Mayor-Cucapah earthquake in Mexico. Static displacements accrue over timescales that mimic the evolution of faulting and become discernible as dynamic displacements dissipate. Note the dramatic increase in permanent offsets for the largest events, increasing from about 5 centimeters for El Mayor to over 4 meters for Tohoku. The data are freely available from Ruhl et al. [2019].

Large earthquakes both strongly shake and deform the region around the source fault to extents that GNSS can easily resolve (Figure 1). With the expansion of GNSS networks and continuous telemetry, seismic monitoring based on GNSS measurements has come online over the past few years, using continuously gathered position data from more than a thousand ground stations, a number that is steadily growing. Station positions are computed in a global reference frame at an accuracy of a few centimeters within 1–2 seconds of data acquisition in the field. In the United States, these data are fed into U.S. Geological Survey (USGS) and National Oceanic and Atmospheric Administration (NOAA) centers charged with generating and issuing earthquake and tsunami early warnings.

In the scenario above, GNSS-based monitoring would provide an immediate discriminant of earthquake size based on the amount of displacement along the coast of Washington state. Were it a magnitude 7, a dozen or so GNSS stations spread along a roughly 30-kilometer span of the coast might reasonably move a few tens of centimeters within half a minute, whereas a magnitude 8 event—or a magnitude 9 “full rip” along the entire subduction zone, from California to British Columbia—would move hundreds of Cascadia GNSS stations many meters. Ground offset at some might exceed 10 meters, depending on location, but the timing of the offsets along the coast determined with GNSS would track the rupture itself.

The July 2019 strike-slip earthquake sequence in the Eastern California Shear Zone near Ridgecrest in the eastern Mojave Desert provided the first real-world demonstration of the capability of GNSS-based seismic monitoring. The newly developed GNSS monitoring systems included a dozen GNSS stations from the National Science Foundation–supported Network of the Americas (NOTA) located near the fault rupture. Data from these stations indicated that the magnitude 7.1 main shock on 5 July caused coseismic offsets of up to 70 centimeters in under 30 seconds of the initiation of fault slip.

The magnitude 7.1 strike-slip earthquake that occurred in the Mojave Desert near Ridgecrest, Calif., on 5 July 2019 caused the ground surface to rupture. Nearby Global Navigation Satellite Systems (GNSS) stations recorded up to 70 centimeters of offset within 30 seconds of the fault rupture. Credit: U.S. Geological Survey

Further analysis of the data showed that those 30 seconds encompassed the fault rupture duration itself (roughly 10 seconds), another 10 or so seconds as seismic waves and displacements propagated from the fault rupture to nearby GNSS stations, and another few seconds for surface waves and other crustal reverberations to dissipate sufficiently such that coseismic offsets could be cleanly estimated. Latency between the time of data acquisition in the Mojave Desert to their arrival and processing for position at Central Washington University was less than 1.5 seconds, a fraction of the fault rupture time itself. Comparison of the coseismic ground deformation estimated within 30 seconds of the event with that determined several days later, using improved GNSS orbital estimates and a longer data window, shows that the real-time offsets were accurate to within 10% of the postprocessed “true” offsets estimated from daily positions [Melgar et al., 2019]. Much of the discrepancy may be attributable to rapid fault creep in the hours after the earthquake.

A Vital Addition for Hazards Monitoring

This new ability to accurately gauge the position of GNSS receivers within 1–2 seconds from anywhere on Earth has opened a new analysis pipeline that remedies known challenges for our existing arsenal of monitoring tools. Receiver position data streams, coupled to existing geophysical algorithms, allow earthquake magnitudes to be quickly ascertained via simple displacement scaling relationships [Crowell et al., 2013 Geophysical Research Letters]. Detailed information about fault orientation and slip extent and distribution can also be mapped nearly in real time as a fault ruptures [Minson et al., 2014 JGR Solid Earth]. These capabilities may prove particularly useful for earthquake early warning systems: GNSS can be incorporated into these systems to rapidly constrain earthquake magnitude, which determines the areal extent over which warnings are issued for a given shaking intensity [Ruhl et al., 2017 Geophysical Research Letters].

GNSS will never replace seismometers for immediate earthquake identifications because of its vastly lower sensitivity to small ground displacements. But for large earthquakes, GNSS will likely guide the issuance of rapid-fire revised warnings as a rupture continues to grow throughout and beyond the timing of initial, seismometer-based characterization [Murray et al., 2019 Seismological Research Letters].

Deformation measured using GNSS is also useful in characterizing tsunamis produced by earthquakes, 80% of which in the past century were excited either by direct seismic uplift or subsidence of the ocean floor along thrust and extensional faults [Kong et al., 2015 UNESCO UNESDOC Digital Library] or by undersea landslides, such as in the 2018 Palu, Indonesia, earthquake (A. Williamson et al., Coseismic or landslide? The source of the 2018 Palu tsunami, EarthArXiv, https://doi.org/10.31223/osf.io/fnz9j). Rough estimates of tsunami height may be computed nearly simultaneously with fault slip by combining equations describing known hydrodynamic behavior with seafloor uplift determined from GNSS offsets [Melgar et al., 2016 Geophysical Research Letters]. Although GNSS won’t capture landslides or other offshore processes for which on-land GNSS has little resolution, the rapidity of the method in characterizing tsunami excitation, compared with the 10–20 minutes required by global tide gauge and seismic networks and by NOAA’s tsunami-specific Deep-Ocean Assessment and Reporting of Tsunamis (DART) buoy system, offers a dramatic potential improvement in response time for local tsunamis that can inundate coastlines within 5–15 minutes of an earthquake.

Natural hazards monitoring using GNSS isn’t limited to just solid Earth processes. Other measurable quantities, such as tropospheric water content, are estimated in real time with GNSS and are now being used to constrain short-term weather forecasts. Likewise, real-time estimates of ionospheric electron content from GNSS can help identify ionospheric storms (space weather) and in mapping tsunami-excited gravity waves in the ionosphere to provide a more direct measurement of the propagating tsunami as it crosses oceanic basins.

A Future of Unimaginable Potential

Many resources beyond the rapid proliferation of GNSS networks themselves have contributed to making global GNSS hazards monitoring a reality. Unlike seismic sensors that measure ground accelerations or velocities directly, GNSS positioning relies on high-accuracy corrections to the orbits and clocks broadcast by satellites. These corrections are derived from continuous analyses of global networks of ground stations. Similarly, declining costs of continuous telemetry have facilitated multiconstellation GNSS processing, using the vast investments in international satellite constellations to further improve the precision and reliability of real-time GNSS measurements of ground displacements.

In the future, few large earthquakes in the western United States will escape nearly instantaneous measurement by real-time GNSS. Throughout the seismically active Americas, from Alaska to Patagonia, numerous GNSS networks in addition to NOTA now operate, leaving big earthquakes without many places to hide. Mexico operates several GNSS networks, as do Central and South American nations from Nicaragua to Chile. Around the Pacific Rim, Japan, New Zealand, Australia, and Indonesia all operate networks that together comprise thousands of ground stations.

In North America, nearly all GNSS networks have open data-sharing policies [Murray et al., 2018]. But a global system for hazard mitigation can be effective only if real-time data are shared among a wider set of networks and nations. The biggest remaining impediment to expanding a global system is increasing the networks whose data are available for monitoring. GNSS networks are expensive to deploy and maintain. Many networks are built in whole or in part for land surveying and operate in a cost-recovery mode that generates revenue by selling data or derived positioning corrections through subscriptions. At the current time, just under 3,000 stations are publicly available for hazards monitoring, but efforts are under way to create international data sharing agreements specifically for hazard reduction. The Sendai Framework for Disaster Risk Reduction, administered by the United Nations Office for Disaster Risk Reduction, promotes open data for hazard mitigation [International Union of Geodesy and Geophysics, 2015], while professional organizations, such as the International Union of Geodesy and Geophysics, promote their use for tsunami hazard mitigation [LaBrecque et al., 2019].

The future holds unimaginable potential. In addition to expanding GNSS networks, modern smartphones by the billions are ubiquitous sensing platforms with real-time telemetry that increasingly make many of the same GNSS measurements that dedicated GNSS receivers do. Crowdsourcing, while not yet widely implemented, is one path forward that could use tens of millions of phones, coupled to machine learning methods, to help fill in gaps in ground displacement measurements between traditional sensors.

The potential of GNSS as an important supplement to existing methods for real-time hazards monitoring has long been touted. However, a full real-world test and demonstration of this capability did not occur until the recent Ridgecrest earthquake sequence. Analyses are ongoing, but so far the conclusion is that the technique performed exactly as expected—which is to say, it worked exceedingly well. GNSS-based hazards monitoring has indeed arrived.

Acknowledgments

Development of global GNSS seismic analysis is supported by NASA-ESI grants NNX14AQ40G and 80NSSC19K0359 and USGS Cooperative Agreements G17AC00344 and G19AC00264 to Central Washington University. Data from the Network of the Americas are provided by the Geodetic Facility for the Advancement of Geoscience (GAGE), operated by UNAVCO Inc., with support from the National Science Foundation and NASA under NSF Cooperative Agreement EAR-1724794.

References

Crowell, B. W., et al. (2013), Earthquake magnitude scaling using seismogeodetic data, Geophys. Res. Lett., 40(23), 6,089–6,094, https://doi.org/10.1002/2013GL058391.

International Union of Geodesy and Geophysics (2015), Resolution 4: Real-time GNSS augmentation of the tsunami early warning system, iugg.org/resolutions/IUGGResolutions2015.pdf.

Kong, L. S. L., et al. (2015), Pacific Tsunami Warning System: A Half-Century of Protecting the Pacific 1965–2015, 188 pp., Int. Tsunami Inf. Cent., Honolulu, Hawaii, unesdoc.unesco.org/ark:/48223/pf0000233564.

LaBrecque, J., J. B. Rundle, and G. W. Bawden (2019), Global navigation satellite system enhancement for tsunami early warning systems, in Global Assessment Report on Disaster Risk Reduction, U.N. Off. for Disaster Risk Reduct., Geneva, Switzerland, unisdr.org/files/66779_flabrequeglobalnavigationsatellites.pdf.

Melgar, D., et al. (2016), Local tsunami warnings: Perspectives from recent large events, Geophys. Res. Lett., 43(3), 1,109–1,117, https://doi.org/10.1002/2015GL067100.

Melgar, D., et al. (2019), Real-time high-rate GNSS displacements: Performance demonstration during the 2019 Ridgecrest, CA earthquakes, Seismol. Res. Lett., in press.

Minson, S. E., et al. (2014), Real-time inversions for finite fault slip models and rupture geometry based on high-rate GPS data, J. Geophys. Res. Solid Earth, 119(4), 3,201–3,231, https://doi.org/10.1002/2013JB010622.

Murray, J. R., et al. (2018), Development of a geodetic component for the U.S. West Coast Earthquake Early Warning System, Seismol. Res. Lett., 89(6), 2,322–2,336, https://doi.org/10.1785/0220180162.

Murray, J. R., et al. (2019), Regional Global Navigation Satellite System networks for crustal deformation monitoring, Seismol. Res. Lett., https://doi.org/10.1785/0220190113.

Ruhl, C. J., et al. (2017), The value of real-time GNSS to earthquake early warning, Geophys. Res. Lett., 44(16), 8,311–8,319, https://doi.org/10.1002/2017GL074502.

Ruhl, C. J., et al. (2019), A global database of strong-motion displacement GNSS recordings and an example application to PGD scaling, Seismol. Res. Lett., 90(1), 271–279, https://doi.org/10.1785/0220180177.

See the full article here .

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Earthquake Alert

Earthquake Alert

Earthquake Network projectEarthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

Get the app in the Google Play store.

Smartphone network spatial distribution (green and red dots) on December 4, 2015

Meet The Quake-Catcher Network

Quake-Catcher Network

The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

Below, the QCN Quake Catcher Network map

ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

Watch a video describing how ShakeAlert works in English or Spanish.

The primary project partners include:

United States Geological Survey
California Governor’s Office of Emergency Services (CalOES)
California Geological Survey
California Institute of Technology
University of California Berkeley
University of Washington
University of Oregon
Gordon and Betty Moore Foundation

The Earthquake Threat

Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

Part of the Solution

Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

System Goal

The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

Current Status

The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

Authorities

The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

For More Information

Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
rdegroot@usgs.gov
626-583-7225

Learn more about EEW Research

ShakeAlert Fact Sheet

ShakeAlert Implementation Plan

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Stem Education Coalition

Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

From AGU GeoSpace Blog: “Forces from Earth’s spin may spark earthquakes and volcanic eruptions at Mount Etna”

From From AGU GeoSpace Blog

26 December 2019
Erin I. Garcia de Jesus

New research suggests forces pulling on Earth’s surface as the planet spins may trigger earthquakes and eruptions at volcanoes.

Seismic activity and bursts of magma near Italy’s Mount Etna increased when Earth’s rotational axis was furthest from its geographic axis, according to a new study comparing changes in Earth’s rotation to activity at the well-known Italian volcano.

Earth’s spin doesn’t always line up perfectly with its north and south poles. Instead, the geographic poles often twirl like a top around Earth’s rotational axis when viewed from space. Every 6.4 years, the axes line up and the wobble fades for a short time – until the geographic poles move away from the spin axis and begin to spiral once again.

Polar motion describes the motion of the Earth’s spin axis (shown in orange) with respect to the geographic north and south poles (shown in blue). Over time, the geographic poles appear to spin away from the spin axis when viewed from space and then back again. Viewed from the perspective of someone on Earth, the spin axis instead appears to spiral away from the geographic poles and then spiral back. The motion of the spin pole with respect to the geographic poles fixed to the Earth’s crust is called polar motion. Note: The size and speed of the spiral are greatly exaggerated for clarity. Video credit: NASA/GSFC Science Visualization Studio.

This phenomenon, called polar motion, is driven by changes in climate due to things like changing seasons, melting ice sheets or movement from tectonic plates. As polar motion fluctuates, forces pulling the planet away from the sun tug at Earth’s crust, much like tides due to the gravitational pull from the sun and moon. The tide from polar motion causes the crust to deform over the span of seasons or years. This distortion is strongest at 45 degrees latitude, where the crust moves by about 1 centimeter (0.4 inches) per year.

Now, a new study published in AGU’s journal Geophysical Research Letters suggests that polar motion and subsequent shifts in Earth’s crust may increase volcanic activity.

“I find it quite exciting to know that while climate drives Earth’s spin, its rotation can also drive volcanoes and seismicity,” said Sébastien Lambert, a geophysicist at Paris Observatory in France and lead author of the study.

The new findings, however, don’t allow scientists to forecast volcanic activity. Although the study suggests earthquakes might be more common or volcanic eruptions may eject more lava when the distance between Earth’s geographic and rotational axes is at its peak, the timescale is too large for meaningful short-term forecasts, according to the authors.

But the results point to an interesting concept. “It’s the first time we’ve found this relationship in this direction from Earth’s rotation to volcanoes,” Lambert said. “It’s a small excitation process, but if you accumulate a small excitation over a long time it can lead to measurable consequences.”

Shaking Earth

Previous work [not presented here] has shown the length of a day on Earth, which changes based on the speed of Earth’s spin, also deforms the crust and could affect volcanic behavior. In the new study, Lambert and his colleague, Gianluca Sottili, a volcanologist from Sapienza University of Rome in Italy, wanted to study the relationship between polar motion and volcanic activity.

They focused on Mount Etna because the volcano is well-studied, meaning there’s plenty of data, and it sits just south of 45 degrees latitude. There also weren’t any volcanic crises out of the ordinary at Mount Etna during the study period, which might otherwise mask the signal from polar motion.

An image of an eruption at Mount Etna on October 30, 2002 from the International Space Station. The eruption, triggered by a series of earthquakes, was one of the most vigorous in years. Ashfall was reported in Libya, more than 350 miles away. Credit: NASA

Lambert and Sottili used seismic records from 11,263 earthquakes that happened within 43 kilometers (26.7 miles) of Mount Etna’s summit between 1999 and 2019. The team also used records of how much magma erupted from the volcano since 1900. They included 62 eruptions in the analysis, based on the time span between events.

The pair then compared the distance between the geographic and rotational poles at the time each event occurred to determine whether volcanic activity was connected to Earth’s rotation.

Lambert and Sottili discovered there were more earthquakes when Earth’s rotational pole was furthest from the geographic axis – at the point in Earth’s top-like spin when it looks like it is about to fall over. Between 1999 and 2019, those peaks were in 2002 and 2009. An expected peak in 2015 never materialized because one of the oscillations contributing to polar motion has been slowing down.

The team also uncovered a link between the amount of magma ejected during an eruption. Polar motion appears to drive the largest eruptions from Mount Etna, although to a lesser extent than its seismic activity, according to the researchers.

Examining volcanoes in the Ring of Fire to see if Earth’s spin impacts their activity would surely be interesting, Sottili said, who was senior author of the study. Even expanding to other planets might open scientists’ view of how external forces impact volcanoes on the surface, he added.

See the full article here .

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GeoSpace is a blog on Earth and space science, managed by AGU’s Public Information staff. The blog features posts by AGU writers and guest contributors on all sorts of relevant science topics, but with a focus on new research and geo and space sciences-related stories that are currently in the news.

Do you have ideas on topics we should be covering? Would you like to contribute a guest post to the blog? Contact Peter Weiss at pweiss@agu.org.

From Horizon The EU Research and Innovation Magazine: “The ‘slow earthquakes’ that we cannot feel may help protect against the devastating ones”

From Horizon The EU Research and Innovation Magazine

10 December 2019
Sandrine Ceurstemont

Unlike regular earthquakes, which can cause visible damage, slow earthquakes cannot be felt at the Earth’s surface. Image credit – Pixabay/ marcellomigliosi1956, licensed under pixabay license

Earthquakes are sudden and their shaking can be devastating. But about 20 years ago, a new type of earthquake was discovered. We cannot feel them, and geologists still know very little about them, such as how often they occur.

Regular earthquakes occur when rock underground breaks along a fault – a crack in the Earth’s crust that commonly forms a boundary between tectonic plates – and slips at a speed of about a metre per second.

The tectonic plates of the world were mapped in 1996, USGS.

Previously, it was thought that unless there’s an earthquake, faults move very slowly, at fingernail growth rate. Then, better earthquake-detection instruments revealed that there is a whole range of slip speeds in between. These are known as slow earthquakes and can last days, months or sometimes even years.

‘Earth movement accelerates but it doesn’t accelerate to the point where it makes an earthquake that can be felt on the surface,’ said Dr Ake Fagereng, a geologist at Cardiff University in the UK.

There are still many questions to be answered about slow earthquakes though. How they happen, for example, still isn’t clear, as well as what the repercussions might be.

Dr Fagereng and his colleagues are especially interested in slow earthquakes’ relationship to regular ones and the conditions that give rise to these events, which they are investigating as part of a project called MICA. ‘If we can figure that out, then we can hopefully also get at whether those conditions can change so that an earthquake speeds up,’ said Dr Fagereng.

In addition to drilling into an offshore area in New Zealand that experiences slow earthquakes, the team has been visiting regions in Japan, Namibia, Cyprus and the UK that would have experienced them in the past. Since they occur deep below the surface of the Earth, which is hard to study, the researchers have chosen areas that were once at the appropriate depths and conditions but have been brought to the surface over time due to erosion and uplift.

‘We are looking for structures that formed (as a result of slow earthquakes) and what they tell us about how the rocks accommodated that slip,’ said Dr Fagereng.

Exposed areas of rock on Kyushu Island, southern Japan, are among those being studied by researchers for evidence of past slow earthquakes. Image credit – Ake Fagareng

Creep

Their theory is that slow earthquakes occur when creep – tiny, continuous movements in a fault – accelerates throughout the fault zone, which can be several kilometres thick. Their field observations showed that a fault can be made up of different rock types of varying strength, such as solid basalt and granite and weaker clay-rich sediment. They suspected that stronger rocks start to fracture as creep speeds up due to weaker rocks moving around them but couldn’t explain exactly why.

Using information from their fieldwork, they’ve now developed a mathematical model to reproduce their theory and describe some of the physics behind it. A mixture of rocks with different deformation styles – such as breaking or bending – seems to be key. A proportion of creeping weak rock is required, as well as locally high enough pressure to cause some rock to rupture.

‘A possibility for these slow earthquakes is that you have a thick creeping zone with embedded stronger (rock) bits,’ said Dr Fagereng.

The team is planning to follow up with more field observations to refine their model. They still can’t explain why slow earthquakes occur at particular locations, for example, and why they are much more predictable than regular earthquakes, often occurring at set intervals.

Dr Fagereng thinks that findings from the project could help improve earthquake and tsunami forecasting. Last year, researchers found the first evidence of a slow earthquake preceding a regular earthquake in an area west of Fairbanks, Alaska, in the US. But the link between the two types of tremors isn’t well understood. In some cases, slow earthquakes could also alleviate stress that would otherwise build up and cause a larger earthquake.

‘We’re hoping to get somewhere on what the relation is between slow earthquakes and regular earthquakes,’ said Dr Fagereng. ‘And then that could potentially feed into models for what size earthquake you can get in different regions.’

Lab experiments could also shed light on the physics of slow earthquakes. Dr Nicolas Brantut from University College London in the UK and his colleagues are using bespoke machines that can deform rock samples at high pressures and temperatures to mimic conditions deep below the surface of the Earth.

Brittle-plastic transition

His team is particularly interested in the brittle-plastic transition, a region about 10 to 15 kilometres below the surface where the behaviour of rocks changes. Above this zone they are brittle, whereas beneath it they flow due to the high temperature and pressure which increase with depth. ‘The brittle part is where you have earthquakes,’ said Dr Brantut.

However, slow earthquakes seem to occur in the brittle-plastic zone, based on seismological observations. In many cases, they also take place at the same temperature and pressure conditions found in this region. But so far, slow slip events have typically been modelled based on the frictional forces at a fault without taking into account the peculiarities of the brittle-plastic transition zone where rocks start to flow.

‘The interactions between friction mechanisms and plastic flow mechanisms are not understood well enough to rule them out as mechanisms for slow earthquakes,’ said Dr Brantut.

As part of the RockDEaF project, Dr Brantut and his team are investigating the motion of rocks at the brittle-plastic transition. They are replicating the conditions in this region on pieces of rock centimetres long to see whether they fracture or flow. ‘We want to understand how these mechanisms compete with each other,’ said Dr Brantut.

Simulating

So far, the team has examined the brittle-plastic transition by simulating a fault in the Earth’s crust in a block of marble. They investigated the behaviour of the rock at different pressures and were expecting to find a sharp transition between brittle and plastic behaviour.

However, they were surprised to find that both behaviours occurred simultaneously under a wide range of pressure conditions. ‘This is something that I think nobody has realised before,’ said Dr Brantut. ‘The fact that we can have both friction and deformation in a continuum at the same time.’

Dr Brantut thinks that results from the project could help pin down where slow earthquakes could occur by determining the conditions and properties of rock that are required.

But they could also provide new clues about the depths at which regular earthquakes originate. Temperature below the surface of the Earth increases as a function of depth, which is typically an increase of 10°C to 40°C per kilometre in the crust. An earthquake’s lowest point of origin is thought to coincide with depths that reach 600°C, since rocks become supple when they surpass this temperature and therefore can’t fracture and generate an earthquake. However better understanding of the transition in rock behaviour should help determine if temperature is the deciding factor.

‘We should understand more about what really controls how deep we can expect earthquakes to propagate,’ said Dr Brantut.

See the full article here .

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From Eos: “A New Dimension to Plate Tectonics”

AGU

From Eos

10.28.19
Kate Wheeling

It’s easy to forget that plate tectonics is a relatively young theory. Researchers have known for only a little more than half a century that Earth’s lithosphere is essentially a jigsaw puzzle of rocky plates sitting on top of a viscous mantle. The plates violently collide, rip apart, or sideswipe each other, usually in excruciatingly slow motion.

Crucial to the theory of plate tectonics is subduction, the process in which a plate of dense oceanic crust collides with a plate of less dense crust and sinks into the mantle. Since the 1960s, scientists have shown that subduction zones are particularly important for driving processes like mountain building and seismic hazards like earthquakes, tsunamis, and volcanoes. But less well understood is how the three-dimensional structure of subduction zones can influence these phenomena.

Two main things have held scientists back from studying the structure of subduction zones, according to Gavin Hayes, a geophysicist at the U.S. Geological Survey (USGS): a lack of data on the 3-D geometry of subducting plates (also known as slabs) and a lack of computing power and software that would allow researchers to visualize these zones in three dimensions. But that’s all beginning to change.

Researchers now are benefiting from new tools to peek inside Earth’s interior, and massive leaps in computing power are allowing scientists to constrain and visualize the 3-D structure of slabs. These new 3-D models are providing critical insights into long-standing gaps in geology’s unifying theory of plate tectonics, including why some mountains arise and some earthquakes occur hundreds of kilometers away from plate boundaries.

“It’s quite an exciting time for this type of science,” Hayes said.

From 2-D to Reality

“Traditionally, seismologists and geodynamicists have been focused on a two-dimensional or cross-sectional viewpoint when studying subduction zones,” said Kirstie Haynie, a USGS Mendenhall Research Fellow.

Cross-sectional diagrams like this one are great starting points for understanding subduction zone dynamics. Credit: K. D. Schroeder, CC-BY-SA 4.0

Even school-age children are familiar with the two-dimensional cross sections of one plate diving beneath another and disappearing into the mantle. Such images are good approximations of subduction zone dynamics, according to experts, and useful for, say, describing the tectonic setting of a recent earthquake. But they can’t convey much about the three-dimensional geometry of the underlying slabs.

There has been an explosion of seismic data over the past 3 decades, as seismic recording stations have proliferated and new tools like seismic tomography [Physics of the Earth and Planetary Interiors] have emerged. These technologies have helped scientists like Hayes build databases like Slab2 [Science], which models the 3-D structure of slabs in subduction zones around the world.

“Seismic tomography is kind of like a CT [computerized tomography] scan of Earth’s interior,” Haynie said. The technique tracks the movement of seismic waves generated by earthquakes as they bounce off underground features, allowing researchers to reconstruct images of inner Earth. What all these new data show is that subduction zones are highly variable.

“What we’re seeing is that even in one subduction zone, the geometry of the downgoing plate varies—in its sense of curvature, in the inclination of the subduction zone, and also how deep the subducted plate goes,” said Margarete Jadamec, a geodynamicist and assistant professor at the University of Buffalo in New York.

Last year, Jadamec and colleagues [Earth and Space Science] fed data on slab morphologies into an open-source visualization software called the ShowEarthModel to create 3-D videos [Earth and Space Science] of every major subduction zone around the world.

“These virtual tours of the various subduction zones are a way for researchers to build a mental picture of what the subduction zone looks like in 3-D,” Jadamec said. “You realize with these movies that a 2-D representation is inadequate because we can actually see in three dimensions [that] the slab varies.”

The data points are tied to their geographic location on the virtual Earth, so viewers can see exactly where the slab geometries are changing. “It forces you to honor the data,” Jadamec said.

Armed with better data and more accurate renderings of what slabs and subduction zones look like, researchers can begin asking questions about how their geometry influences seismic hazards and processes like mantle flow. And evidence is mounting that the 3-D geometry of slabs has a significant impact on the geologic processes taking place at plate boundaries. This has helped Jadamec and others address some long-standing gaps in the original theory of plate tectonics.

A Mystery Solved

“Inherent in the theory of plate tectonics is that the plates are actually rigid, and the deformation is concentrated at the boundaries,” Jadamec said. But that’s not what we actually see on Earth. “What we find in many locations is that we have mountain building and earthquakes that occur far from the plate boundary, like 500 or 1,000 kilometers away,” she said.

Take Alaska, which sits atop the North American plate just where it meets the Pacific plate. The state has mountain ranges, volcanoes, and earthquakes in areas where the simple theory of plate tectonics wouldn’t have predicted them.

For instance, there are tall mountains near the Alaska-Aleutian subduction zone where the plates converge, but Denali, the tallest mountain peak in North America, is some 500 kilometers inland in the Central Alaska Range. Researchers long wondered why the deformation occurred so far from the plate boundary.

Alaska also has some unusual volcanoes. Volcanoes tend to form directly over subduction zones, but in some locations, including in Alaska, they pop up off to the side of subducting slabs.

Finally, Alaska is also the site of the second-largest earthquake ever recorded with modern seismometers, the magnitude 9.2 temblor known as the Great Alaska earthquake of 1964 or the Good Friday earthquake.

To better understand these anomalies, Jadamec created one of the first large-scale 3-D geodynamic simulations of the subduction zone in the region. This allowed her to study the area in southeastern Alaska where the slab comes to an end.

Until recently, researchers tended to ignore slab edges because it was too complex to numerically model the ways in which the mantle arcs around the slab edge, a process called toroidal flow that was first demonstrated in laboratory experiments.

In the first studies of 3-D flow dynamics, researchers used tanks filled with a gooey medium like honey to stand in for the mantle, pressed hard slabs into it, and tracked the flow of the viscous liquid around the edges. As computing resources advanced, researchers like Jadamec began using computational fluid dynamics simulations.

“One of the things that the 3-D slab models like the fluid dynamics experiments show is that in addition to toroidal flow, you get vertical upwelling zones,” Jadamec said. “These upwelling zones seem to spatially correlate with where we observe those anomalous volcanoes on Earth’s surface.”

Building on this work, Jadamec and Haynie went looking for an explanation for Denali in the slab geometry data and found one. “In south central Alaska, there’s a segment of the slab that’s horizontal or flat beneath the overriding plate,” Haynie said. “We think it’s coupled strongly to the overriding plate and that the flat slab is kind of pulling that overriding plate along the path of subduction.”

When Jadamec’s numerical model accounted for both the flat slab and the activity of a nearby strike-slip fault known as the Denali fault, it was able to accurately predict uplift exactly where Denali is located.

That coupling might also explain why the region is prone to such large earthquakes, according to Haynie, but she cautions that there are other factors at play in subduction zones besides the dip angle that could contribute to seismogenesis. Several other studies that look at slab geometries and earthquakes suggest that flat slabs have a role in generating large quakes, including a 2016 paper in Science that found that the biggest historic quakes tended to correlate with areas where 3-D subduction geometry models show that the subducting slab is broad and flat.

“I still think it’s an open question exactly what role subducting geometry plays in big earthquakes,” Hayes said. “But we’re beginning to build the data sets that allow us to better address these questions.”

From Earth to the Cloud

The major challenge now is that our understanding of the 3-D geometries of these underground slabs is “incomplete and constantly changing,” said Haynie, who is building a cloud-based version of the USGS Slab database that can be constantly updated, so that researchers working with them will always have the most up-to-date information feeding their models. “Every earthquake is a new data point.”

The USGS is focused on mitigating hazards. “We’re trying to use these geometries to inform things like our seismic hazard maps, and our understanding of seismic hazards more broadly, so that we can hopefully better mitigate [the damage from] these big earthquakes in the future,” Hayes said. But he notes that these 3-D geometries can also help answer questions about where volcanoes and mountain ranges form.

“These are questions that have been addressed before,” Hayes said, “but now that we’re getting these better data sets, it’s important that we revisit them and see [whether] some of the theories that we’ve thrown out in the past 50 years have held up.”

See the full article here .

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Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

From Lawrence Berkeley National Lab: “New Sensor Could Shake Up Earthquake Response Efforts”

From Lawrence Berkeley National Lab

July 11, 2019
Christina Procopiou

Berkeley Lab technology could reduce time needed to declare buildings affected by earthquakes safe and sound.

(Credit: iStockphoto)

Last week’s massive southern California earthquakes shut down Ridgecrest Regional Hospital throughout the July 4 holiday weekend while the tiny town of Ridgecrest assessed the damages. A new optical sensor developed at Lawrence Berkeley National Laboratory (Berkeley Lab) could speed up the time it takes to evaluate whether critical buildings like these are safe to occupy shortly after a major earthquake.

The technology – which autonomously captures and transmits data depicting the relative displacement between two adjacent stories of a shaking building – is able to provide reliable information about building damage immediately following an earthquake, and could expedite efforts to safely assess, repair, and reoccupy buildings post-quake.

Scientists and engineers at Berkeley Lab, Lawrence Livermore National Laboratory, and the University of Nevada-Reno began working to design an optical method of measuring interstory drift within buildings in 2015. After four years of extensive peer-reviewed research and simulative testing at the University of Nevada’s Earthquake Engineering Laboratory, the Discrete Diode Position Sensor (DDPS) will be deployed for the first time this summer in a multi-story building at Berkeley Lab – which sits adjacent to the Hayward Fault, considered one of the most dangerous faults in the United States.

“Until now, there’s been no way to accurately and directly measure drift between building stories, which is a key parameter forassessing earthquake demand in a building,” said David McCallen, a senior scientist in the Energy Geosciences Division at Berkeley Lab and faculty member at the University of Nevada, who leads the research collaboration.

The debut of DDPS comes as governments at every level make post-earthquake building inspection and reoccupation a central focus of response planning, and as the highly anticipated next generation of remote connectivity – 5G – becomes reality for rapid data transmission. “We are excited that this sensor technology is now ready for field trials, at a time when post-earthquake response strategies have evolved to prioritize safe, continued building functionality and re-occupancy in addition to ‘life safety,’” McCallen said.

DDPS is a small device that will be positioned between building stories to detect interstory drift and transmit data about building damages to response planners. Its debut comes as governments at every level make post-earthquake building inspection and reoccupation a central focus of response planning, and as the highly anticipated next generation of remote connectivity–5G–becomes reality. (Credit Diana Swantek/Berkeley Lab)

Optics makes a difference in monitoring seismic structural health

Measuring building interstory drift has been a factor in assessing buildings for post-earthquake damage for some time, yet finding a reliable method to do so has been fraught with challenges. Traditionally, engineers mounted strong motion earthquake accelerometers at select elevations to secure data on the back-and-forth and side-to-side force imposed on a shaking building. But processing the acceleration data from these instruments to obtain building drift displacements is very challenging due to the frequency limitations of the sensors, especially when buildings have sustained permanent displacements associated with damage. Even more difficult is receiving data quickly enough to inform decision-making on continuity of operations and occupant safety. In addition, because typical building accelerometer-based instrumentation can be quite costly, systems tend to be very sparse with accelerometers on relatively few buildings.

DDPS leverages a promising new alternative for directly measuring building interstory drift that combines laser beams with optical sensors. This technique centers around projecting laser light across a story height to sense the position at which the light strikes a detector located on the adjacent building floor to directly measure structural drift. The tool developed at Berkeley Lab relies on utilizing a laser source and position sensitive detector. Making use of a geometric array of small, inexpensive light-sensitive photodiodes, the sensor is able to instantly track the position of an impinging laser beam.

A new sensor developed at Lawrence Berkeley National Laboratory combines laser beams with a position sensitive detector to directly measure drift between building stories, an essential part of assessing earthquake damages in a building and deeming them safe to reoccupy. (Credit Diana Swantek/Berkeley Lab)

“Previous generations of DDPS were quite a bit larger than the system we are now able to deploy,” says McCallen. “Based on design advancements and lessons learned, the sensor is a quarter of the size of our original sensor design, but features 92 diodes staggered in a rectangular array so that the laser beam is always on one or more diodes.”

So far, DDPS has held up to three rounds of rigorous experimental shake table testing.

“The rigorous testing the DDPS has undergone indicates how the drift displacements measured on the three testbeds compared to representative drifts that could be achieved on an actual full-scale building undergoing strong shaking from an earthquake,” McCallen said.

Why DDPS is smart for cities

The most populous town affected by the earthquakes in southern California earlier this month was Ridgecrest itself, a city of 29,000 which sits at the epicenter of a magnitude 7.1 earthquake which took place on July 5. Even though this is a small population center, the building damage estimates are still in the $100-million range.

If an earthquake of that magnitude were to hit Los Angeles 150 miles to the south of tiny Ridgecrest, or San Francisco, nearly 400 miles north, literally hundreds to thousands of buildings would be at stake for damage. In that scenario, the ability to measure and display key interstory drift information immediately after an earthquake would provide critical new data for making informed decisions on building occupancy – giving first responders information to help guide their efforts to evacuate a building, and municipalities the potential to maintain functional use of important facilities such as hospitals.

In addition, understanding a building’s drift profile would allow a quick determination of building damage potential, letting building inspectors know where to look for potential damage. This will be an important capability in moving beyond time-consuming and challenging manual inspections of hundreds of buildings after the next major urban earthquake.

McCallen noted, “The major earthquakes that struck in southern California this past week serve as a reminder of the risks associated with seismic activity across many regions of the United States. These events put an exclamation point on the need for continued societal focus on earthquake readiness and resilience, including an ability to provide the sensors and data analysis that can rapidly measure infrastructure health and inform the most effective response after the next major quake.”

This research was funded by the U.S. Department of Energy’s (DOE) Nuclear Safety Research and Development (NSR&D) Program managed by the Office of Nuclear Safety within the DOE Office of Environment, Health, Safety and Security. An objective of the NSR&D program is to establish an enduring Departmental commitment and capability to utilize NSR&D in preventing and/or reducing high consequence-low probability hazards and risks posed by DOE and NNSA nuclear facilities, operations, nuclear explosives, and environmental restoration activities.

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Bringing Science Solutions to the World

In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

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From Caltech: “Lessons from the 1994 Northridge Quake”

From Caltech

01/17/2014 [Just now in social media]

Written by Cynthia Eller
Contact:
Deborah Williams-Hedges
(626) 395-3227
debwms@caltech.edu

A portion of the Golden State Freeway in Gavin Canyon that collapsed during the 1994 Northridge earthquake. Credit: FEMA

Current Earthquake Research at Caltech

Since the magnitude 6.7 Northridge earthquake 20 years ago (January 17, 1994), researchers at the California Institute of Technology (Caltech) have learned much more about where earthquakes are likely to happen, and how danger to human life and damage to property might be mitigated when they do occur.

“The Northridge quake really heralded the beginning of a new era in earthquake research, not only in southern California, but worldwide,” says Michael Gurnis, John E. and Hazel S. Smits Professor of Geophysics, and director of the Seismological Laboratory at Caltech.

In the years just prior to the Northridge earthquake, Caltech launched a program called TERRAscope supported by the Whittier foundations, which placed high-quality seismic sensors near where earthquakes occur. The Northridge earthquake was, in effect, the first test of TERRAscope in which Caltech scientists could infer the distribution of an earthquake rupture on subsurface faults and directly measure the associated motion of the ground with greater accuracy. “With a modern digital seismic network, the potential of measuring ground shaking in real time presented itself,” says Gurnis. “The real time view also gave first responders detailed maps of ground shaking so that they could respond to those in need immediately after a quake,” adds Egill Hauksson, senior research associate at Caltech.

To give us this new view of earthquakes, Caltech collaborated with the U.S. Geological Survey (USGS) and the California Geological Survey to form TriNet, through which a vastly expanded network of instrumentation was put in place across southern California. Concurrently, a new network of continuously operated GPS stations was permanently deployed by a group of geophysicists under the auspices of the Southern California Earthquake Center, funded by the USGS, NASA, NSF, and the Keck Foundation. GPS data are used to measure displacements as small as 1 millimeter per year between stations at any two locations, making it possible to track motions during, between, and after earthquakes. Similar and even larger networks of seismometers and GPS sensors have now been deployed across the United States, especially EarthScope, supported by the NSF, and in countries around the world by various respective national agencies like the networks deployed by the Japanese government.

Initially, says Gurnis, there were not many large earthquakes to track with the new dense network of broadband seismic instruments and GPS devices. That all changed in December 2004 with the magnitude 9.3 earthquake and resulting tsunami that struck the Indian Ocean off the west coast of Sumatra, Indonesia. Quite abruptly, Caltech scientists had an enormous amount of information coming in from the instrumentation in Indonesia previously deployed by the Caltech Techtonics Observatory with support from the Gordon and Betty Moore Foundation. By the time the magnitude 9.0 Tohoku-Oki earthquake hit northern Japan in 2011, the Seismological Laboratory at Caltech had developed greatly expanded computing power capable of ingesting massive amounts of seismic and geodetic data. Within weeks of the disaster, a team led by Caltech professor of geophysics Mark Simons using data from GPS systems installed by the Japanese had produced extensive measurements of ground motion, as well as earthquake models constrained by this data, that provided new insight into the mechanics of plate tectonics and fault ruptures.

The Tohoku-Oki earthquake was unprecedented: scientists estimate that over 50 meters of slip on the subsurface fault occurred during the devastating earthquake. Currently, scientists at Caltech and the Jet Propulsion Laboratory are prototyping new automated systems for exploiting the wealth of GPS and satellite imaging data to rapidly provide disaster assessment and situational awareness as events occur around the globe. “We are now at a juncture in time where new observational capabilities and available computational power will allow us to provide critical information with unprecedented speed and resolution,” says Simons.

Earthquakes are notable—and, for many, particularly upsetting—because they have always come without warning. Earthquakes do in fact happen quickly and unpredictably, but not so much so that early-warning systems are impossible. In a Moore Foundation-supported collaboration with UC Berkeley, the University of Washington, and the USGS, Caltech is developing a prototype early-warning system that may provide seconds to tens of seconds of warning to people in areas about to experience ground shaking, and minutes of warning to people potentially in the path of a tsunami. Japan invested heavily in an earthquake early-warning system after the magnitude 6.9 Kobe earthquake that occurred January 17, 1995, on the one-year anniversary of the Northridge earthquake, and the system performed well during the Tohoku-Oki earthquake. “It was a major scientific and technological accomplishment,” says Gurnis. “High-speed rail trains slowed and stopped as earthquake warnings came in, and there were no derailments as a result of the quake.”

Closer to home, Caltech professor of geophysics Robert Clayton has aided local earthquake detection by distributing wallet-sized seismometers to residents of the greater Pasadena area to keep in their homes. The seismometers are attached to a USB drive on each resident’s computer, which is to remain on at all times. The data from these seismometers serve two functions: they record seismic activity on a detailed block-by-block scale, and, in the event of a large earthquake, they can help identify areas that are hardest hit. One lesson learned in the Northridge earthquake was that serious damage can occur far from the epicenter of an earthquake. The presence of many seismometers could help first responders to find the worst-affected areas more quickly after an earthquake strikes.

Caltech scientists have also been playing a leading role in the large multi-institutional Salton Seismic Imaging Project. The project is mapping the San Andreas fault and discovering additional faults by setting off underground explosions and underwater bursts of compressed air and then measuring the transmission of the resulting sound waves and vibrations through sediment. According to Joann Stock, professor of geology and geophysics at Caltech, knowing the geometry of faults and the composition of nearby sediments informs our understanding of the types of earthquakes that will occur in the future, and the reaction of the local sediment to ground shaking.

In addition, Caltech scientists learned much through simulating—via both computer modeling and physical modeling techniques—how earthquakes occur and what they leave in their aftermath.

Computer simulations of how buildings respond during earthquakes recently allowed Caltech professors Thomas Heaton, professor of engineering seismology, and John Hall, professor of civil engineering, to estimate the decrease in building safety caused by the existence of defective welds in steel-frame structures, a problem identified after the Northridge earthquake. Researchers simulated the behavior of different 6- and 20-story building models in a variety of potential earthquake scenarios created by the Southern California Earthquake Center for the Los Angeles and San Francisco areas. The study showed that defective welds make a building significantly more susceptible to collapse and irreparable damage, and also found that stiffer, higher-strength buildings perform better than more flexible, lower-strength designs.

Caltech professor of mechanical engineering and geophysics Nadia Lapusta recently used computer simulations of numerous earthquakes to determine what role “creeping” fault slip might play in earthquake events. It has been known for some time that, in addition to the rapid displacements that trigger earthquakes, land also slips very slowly along fault lines, a process that was thought to stop incoming earthquake rupture. Instead, Lapusta’s models show that these “stable segments” may become seismically active in an earthquake, accelerating and even strengthening its motions. Lapusta hypothesizes that this was one factor behind the severity of the 2011 Tohoku-Oki earthquake. Taking advantage of advances in computer modeling, Lapusta and her colleague Jean-Philippe Avouac, Earle C. Anthony Professor of Geology at Caltech, have created a comprehensive model of a fault zone, including both its earthquake activity and its behavior in seismically quiet times.

Physical modeling of earthquakes is carried out at Caltech via collaborative efforts between the Divisions of Geological and Planetary Sciences and of Engineering and Applied Science. A series of experiments conducted by Ares Rosakis, the Theodore von Kármán Professor of Aeronautics and Mechanical Engineering, and collaborators including Lapusta and Hiroo Kanamori, the John E. and Hazel S. Smits Professor of Geophysics, Emeritus, used polymer plates to simulate land masses. Stresses were then created at various angles to the fault lines between the plates to set off earthquake-like activity. The motion in the polymer plates was measured by laser vibrometers while a high-speed camera recorded the movements in detail, yielding unprecedented data on the propagation of seismic waves. Researchers learned that strike-slip faults like the San Andreas may rupture in more than one direction (it was previously believed that these faults had a preferred direction), and that in addition to sliding along a fault, ruptures may occur in a “self-healing” pulselike manner in which a seismic wave “crawls” down a fault line. A third study drew conclusions about how faults will behave—in either a classic cracklike sliding rupture or in a pulselike rupture—depending on the angle at which compression forces strike the fault.

“Northridge was a devastating earthquake for Los Angeles, and there was a massive amount of damage,” Gurnis says, “But in some sense, we stepped up to the plate after Northridge to determine what we could do better. And as a result we have ushered in an era of dense, high-fidelity geophysical networks on top of hazardous faults. We’ve exploited these networks to better understand how earthquakes occur, and we’ve pushed the limits such that we are now at the dawn of a new era of earthquake early warning in the United States. That’s because of Northridge.”

See the full article here .

Earthquake Alert

Earthquake Alert

Earthquake Network projectEarthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

Get the app in the Google Play store.

Smartphone network spatial distribution (green and red dots) on December 4, 2015

Meet The Quake-Catcher Network

Quake-Catcher Network

The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

Below, the QCN Quake Catcher Network map

ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

Watch a video describing how ShakeAlert works in English or Spanish.

The primary project partners include:

United States Geological Survey
California Governor’s Office of Emergency Services (CalOES)
California Geological Survey
California Institute of Technology
University of California Berkeley
University of Washington
University of Oregon
Gordon and Betty Moore Foundation

The Earthquake Threat

Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

Part of the Solution

Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

System Goal

The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

Current Status

The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

Authorities

The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

For More Information

Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
rdegroot@usgs.gov
626-583-7225

Learn more about EEW Research

ShakeAlert Fact Sheet

ShakeAlert Implementation Plan

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Stem Education Coalition

The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

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