From Caltech: “Slow Earthquakes in Cascadia are Predictable”

From Caltech

July 01, 2020

Robert Perkins
(626) 395‑1862
rperkins@caltech.edu

Cascadia subduction zone

Evidence mounts that slow-slip seismic events follow a deterministic pattern.

If there is one word you are not supposed to use when discussing serious earthquake science, it is “predict.” Seismologists cannot predict earthquakes; instead they calculate how likely major earthquakes are to occur along a certain fault over a given period of time.

It is a matter of debate among seismologists whether the process that drives earthquakes—the loading of strain along a fault followed by the sudden, sharp release of energy as two tectonic plates grind against one another—is a stochastic (random) process, for which only an estimate of the probability of occurrence can be made, or whether it is a deterministic, and potentially predictable, process.

Seismologists at Caltech studied a decade’s worth of so-called “slow-slip events,” which result from episodic fault slip like regular earthquakes but only generate barely perceptible tremors, in the Cascadia region of the Pacific Northwest. Their analysis shows that this particular type of seismic event is deterministic and potentially could be predictable days or even weeks in advance.

A paper about the work was published in the journal Science Advances on July 1.

“Deterministic chaotic systems, despite the name, do have some predictability. This study is a proof of concept to show that friction at the natural scale behaves like a chaotic system, and consequently has some degree of predictability,” says Adriano Gualandi, the lead and corresponding author of the paper. Gualandi was a postdoctoral scholar in the lab of Jean-Philippe Avouac, the Earle C. Anthony Professor of Geology and Mechanical and Civil Engineering, while working on this research. Gualandi and Avouac collaborated with Sylvain Michel, who worked on this project as a graduate student at Caltech, and Davide Faranda of Institut Pierre Simon Laplace in France on the study.

Slow-slip events were first noted about two decades ago by geoscientists tracking otherwise imperceptible shifts in the earth using global positioning system (GPS) technology. The events occur when tectonic plates grind incredibly slowly against each other, like an earthquake in slow motion. A slow-slip event that occurs over the course of weeks might release the same amount of energy as a one-minute-long magnitude 7.0 earthquake. However, because these quakes release energy so slowly, the deformation that they cause at the surface is on the scale of millimeters, despite affecting areas that may span thousands of square kilometers.

As such, slow-slip events were only discovered when GPS technology was refined to the point that it could track those very minute shifts. Slow-slip events also do not occur along every fault; so far, they have been spotted in just a handful of locations including the Pacific Northwest, Japan, Mexico, and New Zealand.

Slow-slip events are useful to researchers because they build up and reoccur frequently, making it possible to study how strain loads and releases along a fault. Over a 10-year period, 10 magnitude 7.0 or greater slow-slip earthquakes might occur along a given fault. By contrast, most regular earthquakes of that magnitude only reoccur on the order of hundreds of years. Because of this time lag between regular large earthquakes and the lack of instrumental records from hundreds of years ago, it is impossible to precisely compare past events with recent ones.

GPS stations reveal activity beneath Cascadia where the oceanic floor slides beneath North America. The plate interface is locked at shallow depths (the shaded area), but we see recurring slow-slip events (in blue) that unzip the plate interface, generating tremors (the black dots).

Despite their name, slow-slip events offer seismologists a way to press “fast-forward” on the loading/slipping process that drives earthquakes. In a short time frame of around 10 years, seismologists using state-of-the-art GPS equipment can observe the cycle repeat itself several times.

Slow-slip events represent what is known as a “forced non-linear dynamical system.” The motion of the tectonic plates is the force driving the system, while the friction between the plates, which causes pressure to build up and then eventually be released in a slip event, makes the system non-linear; in a non-linear system, the change in output is not proportional to the change in input. Despite the fact that both the motion and the friction can be modeled using fully deterministic differential equations, the starting conditions of the system—how much strain the fault is already under, for example—have a significant impact on long-term outcomes. Not knowing those exact starting conditions is one of the possible reasons that the overall system is unpredictable in the long run. However, an examination of the fault slip history can reveal how often and for how long similar patterns repeated over time. In this way, the team was able to assess the predictability horizon time of slow-slip events.

“This result is very encouraging,” Gualandi says. “It shows that we are on the right track and, if we manage to get more precise data, we could attempt some real-time prediction experiments for slow earthquakes.”

Gualandi likens the potential prediction of a slow-slip event to the current science of forecasting the weather, which also involves predictions about a complex, chaotic process (and similarly falls off in accuracy after a week or so). “We already know that approximately every 12 to 14 months there will be a new slow earthquake, but we do not know exactly when it will happen. What we have shown is that it seems to be possible to determine when the fault will slip some days before it happens, similar to the way weather can be forecast fairly accurately a couple days in advance.”

One key question is whether the findings for slow-slip quakes can translate to the regular earthquakes that shake cities and endanger lives and property. Last year Michel, Avouac, and Gualandi reported evidence that slow-slip earthquakes are a good analogue for their more destructive cousins.

“If the analogy that we’re drawing between slow earthquakes and regular earthquakes is correct, then regular earthquakes are predictable,” Avouac says. “But even if regular earthquakes are deterministic, the predictability horizon may be very short, possibly on the order of a few seconds, which may be of limited utility. We don’t know yet.”

See the full article here .

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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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From University of Bristol via phys.org: “New research reveals how water in the deep Earth triggers earthquakes and tsunamis”

From University of Bristol

via

phys.org

June 24, 2020

Quill, on the island of Statia. One of the islands in the Lesser Antilles. Credit: Dr George Cooper

In a new study, published in the journal Nature, an international team of scientists provide the first conclusive evidence directly linking deep Earth’s water cycle and its expressions with magmatic productivity and earthquake activity.

Water (H2O) and other volatiles (e.g. CO2 and sulphur) that are cycled through the deep Earth have played a key role in the evolution of our planet, including in the formation of continents, the onset of life, the concentration of mineral resources, and the distribution of volcanoes and earthquakes.

Subduction zones, where tectonic plates converge and one plate sinks beneath another, are the most important parts of the cycle—with large volumes of water going in and coming out, mainly through volcanic eruptions. Yet, just how (and how much) water is transported via subduction, and its effect on natural hazards and the formation of natural resources, has historically been poorly understood.

Lead author of the study, Dr. George Cooper, Honorary Research Fellow at the University of Bristol’s School of Earth Sciences, said:”As plates journey from where they are first made at mid-ocean ridges to subduction zones, seawater enters the rocks through cracks, faults and by binding to minerals. Upon reaching a subduction zone, the sinking plate heats up and gets squeezed, resulting in the gradual release of some or all of its water. As water is released it lowers the melting point of the surrounding rocks and generates magma. This magma is buoyant and moves upwards, ultimately leading to eruptions in the overlying volcanic arc. These eruptions are potentially explosive because of the volatiles contained in the melt. The same process can trigger earthquakes and may affect key properties such as their magnitude and whether they trigger tsunamis or not.”

Exactly where and how volatiles are released and how they modify the host rock remains an area of intense research.

Most studies have focused on subduction along the Pacific Ring of Fire. However, this research focused on the Atlantic plate, and more specifically, the Lesser Antilles volcanic arc, located at the eastern edge of the Caribbean Sea.

“This is one of only two zones that currently subduct plates formed by slow spreading. We expect this to be hydrated more pervasively and heterogeneously than the fast spreading Pacific plate, and for expressions of water release to be more pronounced,” said Prof. Saskia Goes, Imperial College London.

The Volatile Recycling in the Lesser Antilles (VoiLA) project brings together a large multidisciplinary team of researchers including geophysicists, geochemists and geodynamicists from Durham University, Imperial College London, University of Southampton, University of Bristol, Liverpool University, Karlsruhe Institute of Technology, the University of Leeds, The Natural History Museum, The Institute de Physique du Globe in Paris, and the University of the West Indies.

“We collected data over two marine scientific cruises on the RRS James Cook, temporary deployments of seismic stations that recorded earthquakes beneath the islands, geological fieldwork, chemical and mineral analyses of rock samples, and numerical modelling,” said Dr. Cooper.

To trace the influence of water along the length of the subduction zone, the scientists studied boron compositions and isotopes of melt inclusions (tiny pockets of trapped magma within volcanic crystals). Boron fingerprints revealed that the water-rich mineral serpentine, contained in the sinking plate, is a dominant supplier of water to the central region of the Lesser Antilles arc.

“By studying these micron-scale measurements it is possible to better understand large-scale processes. Our combined geochemical and geophysical data provide the clearest indication to date that the structure and amount of water of the sinking plate are directly connected to the volcanic evolution of the arc and its associated hazards,” said Prof. Colin Macpherson, Durham University

“The wettest parts of the downgoing plate are where there are major cracks (or fracture zones). By making a numerical model of the history of fracture zone subduction below the islands, we found a direct link to the locations of the highest rates of small earthquakes and low shear wave velocities (which indicate fluids) in the subsurface,” said Prof. Saskia Goes.

The history of subduction of water-rich fracture zones can also explain why the central islands of the arc are the largest and why, over geologic history, they have produced the most magma.

“Our study provides conclusive evidence that directly links the water-in and water-out parts of the cycle and its expressions in terms of magmatic productivity and earthquake activity. This may encourage studies at other subduction zones to find such water-bearing fault structures on the subducting plate to help understand patterns in volcanic and earthquake hazards,” said Dr. Cooper.

“In this research we found that variations in water correlate with the distribution of smaller earthquakes, but we would really like to know how this pattern of water release may affect the potential—and act as a warning system—for larger earthquakes and possible tsunami,” said Prof. Colin Macpherson.

See the full article here.

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From temblor: “Magnitude-5.9 quake strikes the eastern end of the North Anatolian Fault”

From temblor

June 18, 2020
Haluk Eyidoğan, Ph.D., Professor of Seismology, Istanbul Technical University

A moderate earthquake struck the Bingöl province in eastern Turkey on Sunday. The quake occurred at the intersection between two major faults in the region along a right-lateral strand of the North Anatolian Fault.

On June 14, 2020 (14:26 UTC) in the province of Bingöl in eastern Turkey, near Kaynarpinar village (39.3495 N, 40.7350 E), a strong earthquake occurred. According to Turkish authorities, the shallow — 3.1 mile (5 kilometer) — deep quake registered as a magnitude-5.8. The European Mediterranean Seismic Centre (EMSC) reports it as a magnitude-5.9.

The location of the 14 June 2020 earthquake and other notable quakes in the region.

The number of buildings damaged in the quake is not currently known, but there are reports of significant damage to mudbrick masonry structures and also to a small number of reinforced concrete structures. Official statements report at least one fatality and several people injured.

Junction of the North Anatolian and East Anatolian Faults

The earthquake ocurred where the North Anatolian Fault and the East Anatolian Fault meet. This junction exhibits a rather complicated network of faults of different length that cross one another. Depending on the orientation and magnitude of stress imparted by this earthquake on the faults in the region, I expect that aftershock activity may be prolonged.

Elmali Fault a likely source

The earthquake seems to have struck on the right-lateral strike-slip Elmalı Fault, a 27-kilometer-long branch of the North Anatolian Fault, based on the latest official active fault map in Turkey. Slip on this fault caused a magnitude-6.9 earthquake on August 17, 1949. Regions of high damage correlate to the location of the Elmalı Fault, further suggesting this is the structure that ruptured. The locations of large and moderate magnitude earthquakes are often revised by scientists after review of available data. After the location of this earthquake is revised and finalized, the quake’s relationship with the 40-kilometer-long Kargıpazar Fault, parallel to the Elmalı Fault, will be better understood.

1:1 250 000 Scale Active Fault Map Of Turkey

This map is a guide document which shows the geographic distribution and general characteristics of the active faults of the Turkish mainland. It provides active fault information at a 1:1,250,000 scale for the country. It is published with accompanying explanatory textbook. It does not provide all data to be used in analytical assessments and applications. Click for the larger map view.

Cite this map as follows:

Emre, Ö., Duman, T.Y., Özalp, S., Elmacı, H., Olgun, Ş. and Şaroğlu, F., 2013. Active Fault Map of Turkey with and Explanatory Text. General Directorate of Mineral Research and Exploration, Special Publication Series-30. Ankara-Turkey

After 250 years of quiet, is the Yedisu Fault now in play?

The epicenter of the earthquake is located near the eastern end of the Yedisu Fault, one of the important segments of the North Anatolian Fault. The Yedisu Fault has not generated a strong earthquake in the last 250 years — since 1874, when a magnitude-5.8 quake struck — according to current records. Given the location of this week’s earthquake and the orientation of the fault that likely ruptured, I recommend calculating how much stress the 1874 earthquake — with a right strike-slip fault mechanism — loaded on Yedisu Fault. This analysis may inform futures estimates of earthquake hazard in the region.

Further Reading

Active Faults of Turkey, General Directorate of Mineral Research and Exploration (MTA), Ankara, Turkey.
Duman, T.Y. & Emre, Ö., 2013. The East Anatolian Fault: geometry, segmentation and jog characteristics Geological Society, London, Special Publications, 372, 495-529.

Eyidoğan, H., U. Güçlü, Z. Utku & E. Değirmenci, 1991. Türkiye büyük depremleri makro-sismik rehberi (1900-1988), İstanbul Teknik Üniversitesi, İstanbul, 199 pages.

http://www.koeri.boun.edu.tr/sismo/2/latest-earthquakes/list-of-latest-events/

https://www.emsc-csem.org/Earthquake/earthquake.php?id=867603#summary

See the full article here .

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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 Ohio State University: “‘Wobble’ may precede some great earthquakes, study shows”

From Ohio State University

Apr 29,2020
Laura Arenschield

Credit: CC0 Public Domain

The land masses of Japan shifted from east to west to east again in the months before the strongest earthquake in the country’s recorded history, a 2011 magnitude-9 earthquake that killed more than 15,500 people, new research shows.

Those movements, what researchers are calling a “wobble,” may have the potential to alert seismologists to greater risk of future large subduction-zone earthquakes. These destructive events occur where one of Earth’s tectonic plates slides under another one. That underthrusting jams up or binds the earth, until the jam is finally torn or broken and an earthquake results.

The findings were published today (April 30) in the journal Nature.

“What happened in Japan was an enormous but very slow wobble – something never observed before,” said Michael Bevis, a co-author of the paper and professor of earth sciences at The Ohio State University.

“But are all giant earthquakes preceded by wobbles of this kind? We don’t know because we don’t have enough data. This is one more thing to watch for when assessing seismic risk in subduction zones like those in Japan, Sumatra, the Andes and Alaska.”

The wobble would have been imperceptible to people standing on the island, Bevis said, moving the equivalent of just a few millimeters per month over a period of five to seven months. But the movement was obvious in data recorded by more than 1,000 GPS stations distributed throughout Japan, in the months leading up to the March 11 Tohoku-oki earthquake.

The research team, which included scientists from Germany, Chile and the United States, analyzed that data and saw a reversing shift in the land – about 4 to 8 millimeters east, then to the west, then back to the east. Those movements were markedly different from the steady and cyclical shifts the Earth’s land masses continuously make.

“The world is broken up into plates that are always moving in one way or another,” Bevis said. “Movement is not unusual. It’s this style of movement that’s unusual.”

Bevis said the wobble could indicate that in the months before the earthquake, the plate under the Philippine Sea began something called a “slow slip event,” a relatively gentle and “silent” underthrusting of two adjacent oceanic plates beneath Japan, that eventually triggered a massive westward and downward lurch that drove the Pacific plate and slab under Japan, generating powerful seismic waves that shook the whole country.

That 2011 earthquake caused widespread damage throughout Japan. It permanently shifted large parts of Japan’s main island, Honshu, several meters to the east. It launched tsunami waves more than 40 meters high. More than 450,000 people lost their homes. Several nuclear reactors melted down at the Fukushima Daiichi Nuclear Power Plant, sending a steady stream of toxic, radioactive materials into the atmosphere and forcing thousands nearby to flee their homes. It was the worst nuclear disaster since Chernobyl.

Researchers who study earthquakes and plate tectonics try to pinpoint the approximate magnitude of the next large earthquakes and predict where and when they might occur. The “when” is much harder than the “where.”

But it won’t be possible to use the findings of this study to predict earthquakes in some subduction zones around the world because they don’t have the GPS systems needed, said Jonathan Bedford, lead author of this study and a researcher at the GFZ German Research Centre for Geosciences.

In 2011, Japan had one of the largest and most robust GPS monitoring systems in the world. That system provided ample data, and allowed the research team to identify the swing the land mass made in the months leading up to the earthquake.

Other countries, including Chile and Sumatra, which were hit by devastating earthquakes and tsunamis in 2010 and 2004, respectively, had much less-comprehensive systems at the time of those disasters.

The researchers analyzed similar data from the 2010 Chile earthquake, and found evidence of a similar wobble; Bedford said the data was “only just good enough to capture the signal.”

“We really need to be monitoring all major subduction zones with high-density GPS networks as soon as possible,” he said.

See the full article here .

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The Ohio State University (OSU, commonly referred to as Ohio State) is a public research university in Columbus, Ohio. Founded in 1870 as a land-grant university and the ninth university in Ohio with the Morrill Act of 1862,[4] the university was originally known as the Ohio Agricultural and Mechanical College. The college originally focused on various agricultural and mechanical disciplines but it developed into a comprehensive university under the direction of then-Governor (later, U.S. President) Rutherford B. Hayes, and in 1878 the Ohio General Assembly passed a law changing the name to “The Ohio State University”.[5] The main campus in Columbus, Ohio, has since grown into the third-largest university campus in the United States.[6] The university also operates regional campuses in Lima, Mansfield, Marion, Newark, and Wooster.

The university has an extensive student life program, with over 1,000 student organizations; intercollegiate, club and recreational sports programs; student media organizations and publications, fraternities and sororities; and three student governments. Ohio State athletic teams compete in Division I of the NCAA and are known as the Ohio State Buckeyes. As of the 2016 Summer Olympics, athletes from Ohio State have won 104 Olympic medals (46 gold, 35 silver, and 23 bronze). The university is a member of the Big Ten Conference for the majority of sports.

From temblor: “Faults slip slowly in Cascadia”

From temblor

March 17, 2020
Noel Bartlow, Ph.D., Assistant Researcher, Berkeley Seismology Laboratory

The Cascadia Subduction Zone has occasional large earthquakes and frequent slow-slip events. A new study quantifies how these slow-slip events accommodate tectonic plate motion.

Subduction zones such as the one beneath the U.S. Pacific Northwest and British Columbia are capable of generating very large and destructive earthquakes. But not all of the tectonic motion accommodated in these areas causes earthquakes that can be felt. Episodic tremor and slip, a type of aseismic fault slip or slow slip, accounts for a large amount of fault motion on the deeper extent of the Cascadia Subduction Zone. A new study reveals what this means for future large earthquakes in the region.

Seattle, Wash., sits on top of the Cascadia Subduction Zone. Credit: CommunistSquared

A quiet Cascadia comes to life

Just off the Pacific Northwest coast, the Juan de Fuca Plate collides with the North American Plate. Here, the Juan de Fuca Plate slides beneath North America, forming the Cascadia Subduction Zone. The contact between these two plates, called the plate interface, is stuck due to friction. Slip on the plate interface is necessary to accommodate the collision of the two plates. The Cascadia Subduction Zone plate interface slips every few hundred years in very large earthquakes with magnitudes approaching or even above 9.0. These earthquakes generate dangerous tsunamis similar to the 2011 magnitude-9.0 Tohoku-Oki earthquake and accompanying tsunami in Japan. The last such event in the Cascadia region occurred more than 320 years ago on January 26, 1700.

Map showing the Cascadia subduction zone, the Gorda and Explorer “plates” are part of the larger Juan de Fuca tectonic plate, but move in slightly different directions and can be considered sub-plates.

In between large earthquakes, the plate interface is not silent. Instead it chatters to life every few months with episodic tremor and slip events. In these events, the plate interface slips as it would in an earthquake but takes much longer to do so, releasing the same energy as an earthquake with a magnitude of up to 6.8 over a period of a few days to weeks. These events do not produce dangerous shaking, but they do contain information about how the subduction zone is behaving. An episodic tremor and slip event differs from other slow-slip events in that episodic tremor and slip events recur frequently and are also accompanied by numerous tiny earthquakes called tremor, which are too small for humans to feel.

In a new study published in the journal Geophysical Research Letters, I reveal how much plate motion is accommodated by these events in the Cascadia Subduction Zone.

Using GPS satellites to observe plate motion

Knowing where and how much slip occurs during these events helps scientists understand how they may influence the location and timing of a future large earthquake.

Measuring slip on a plate interface is not as easy as pulling out a yard stick, however.

The plate interface lies below Earth’s surface, so to find out how much slip occurs during these events, we needed to look at what we can see—the ground beneath our feet. This is where satellites come in.

In this study, I used satellite GPS observations to determine how much ground motion occurs during each event. I then calculated how much slip had to occur along the plate interface at depth to account for that ground motion. I tallied up ground motion during these events to find the cumulative effect of all episodic tremor and slip events across the Cascadia Subduction Zone over the last 15-25 years, averaged over time. Applying this systematic approach across the region revealed that not all parts of the subduction zone are behaving the same.

A highly variable system

GPS observations and other data collected over the past few decades show that the Juan de Fuca and North American plates are moving toward each other at 40 millimeters per year in the northern part of the subduction zone near Seattle, and 31 millimeters per year in the southern part near Cape Mendocino, CA. The rate of motion between the two plates defines the “slip budget”, or the total amount of slip that must be accommodated everywhere on the plate interface. I compare this total to the amount released in episodic tremor and slip to understand its role in the overall accommodation of slip on the plate interface.

Episodic tremor and slip events accommodate a highly variable amount of slip along the length of the subduction zone. This has implications for how stress is distributed along the plate interface, and thus where future large earthquakes may nucleate.

In some areas, the slow-slip events account for all of the measured plate convergence. In the very southern part of the subduction zone, slow slip actually releases more slip than the expected convergence rate of the two plates. This might mean that the plates are moving together faster than previous estimates in this region. In other areas of the interface, the slow-slip events accommodate only a fraction of the convergence motion of the two plates—one-fourth or less of the motion in some places. This means that a lot of the motion between the two plates must be released in another way, most likely as steady creep of the plates past one another but potentially also in future earthquakes.

Motions of GPS sites in the Cascadia region during episodic tremor and slip events, modified from Bartlow (2020). Each arrow represents one GPS station and its motion relative to the subducting plate. Motions are greatly exaggerated.

Identifying regions at risk

Previous work on the plate interface in this region revealed the locations where the plate is locked—that is, where friction prevents slip between the two plates (Schmalzle et al., 2014). Large earthquakes occur in these locked sections when the lock is abruptly broken. My results show that slow slip generally occurs in a region offset from the locked section of the plate interface. This means that at present, these events are less likely to trigger large earthquakes than if they were located right at the edge of the locked zone.

The main region of episodic tremor and slip in Cascadia is in an area with no locking. This means that the full slip budget is accommodated by episodic tremor and slip. In the majority of the subduction zone where episodic tremor and slip takes up less than the full slip budget, the plate interface is creeping along at a slower rate between these events.

It is possible that over time the episodic tremor and slip events will migrate closer to the locked zone over time. If this were to occur, it may indicate that the next big earthquake is on the horizon. It is also possible that slow-slip events will become larger or more frequent when a large earthquake is imminent. It is therefore important to monitor episodic tremor and slip in Cascadia over time. The method we applied here can be used to detect these changes and therefore remains an important tool in earthquake hazard monitoring.

A) Time-averaged episodic tremor and slip rate (colors) and contours of density of tremor detections (brown lines) on the Cascadia plate interface (modified from Bartlow, 2020). B) Same as A, but with a comparison to the location of the locked zone (red and yellow colors) from Schmalzle et al. (2014).

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 temblor: “Strong earthquakes on Turkey-Iran border trigger scientific cooperation”

From temblor

March 3, 2020
By Elisabeth Nadin, Ph.D., Associate Professor, University of Alaska Fairbanks, U.S.
Haluk Eyidoğan, Ph.D., Professor of Seismology, Istanbul Technical University, Turkey
Ali Moradi, Ph.D., Director of Iranian Seismological Center and Assistant Professor, Institute of Geophysics, University of Tehran, Iran

*editor’s note: Haluk Eyidoğan and Ali Moradi provided significant insight into this piece, in addition to their attributed material.

On February 23, 2020, two earthquakes struck the Turkey-Iran border. Scientists from both countries are now working to figure out which faults ruptured during this event.

Faults don’t recognize international boundaries. When large earthquakes occur in border regions, scientists are often left piecing together data from different sources to figure out what happened. This is critical to assessing further seismic hazard in the area.

In the early morning hours of February 23, a magnitude 5.8 earthquake rattled the border between Turkey and Iran. That evening, a magnitude 6 quake struck in the same area. Ten days later, geologists in both countries are still trying to figure out exactly which of the numerous faults in this region ruptured.

A cluster of earthquakes recently struck the Turkey-Iran border, destroying or damaging thousands of buildings. Credit: Temblor.

A cluster of earthquakes

The February 23 events were among several notable quakes in the region in recent days. A cluster of earthquakes occurred in northwestern Iran over the past few weeks, including a magnitude-4.7 on 16 February. The magnitude 5.8 caused 10 fatalities in Turkey, more than 100 injuries between the two countries, and thousands of destroyed or damaged buildings. Ten hours later, the magnitude-6 struck within the same cluster.

Although seismic hazard agencies around the world calculate earthquake magnitude and location within minutes to hours of any large event, it can still be difficult to know exactly which fault ruptured, and what its precise orientation is. This information is important to understanding future earthquake risk in a region because in some cases energy released during one earthquake could increase stress on a neighboring fault, driving it toward failure.

Science across borders

Seismologists Haluk Eyidoğan of Turkey and Ali Moradi of Iran are trying to converge on what faults in the region slipped during this series of earthquakes. They suspect that a pair of conjugate faults—two faults that intersect like an “X” through Earth’s crust —is to blame.

The complex network of faults throughout Turkey and Iran result from the tectonic march of the Arabian plate into the Eurasian plate, resulting in the rise of the Zagros mountains. “Conjugate fault structures are a common feature in the eastern Anatolian tectonic region,” notes Eyidoğan.

The two scientists believe that on the Iranian side of the border, the Goharan Fault, oriented northwest–southeast, slipped predominantly by right-lateral motion during the 5.8-magnitude quake. Its conjugate—the other arm of the X—the northeast–southwest-oriented Ravian Fault, slipped by left-lateral motion during the magnitude-6 quake.

As these faults don’t stop just because there is a national border, it is important to know how their traces continue into Turkey. Differing fault naming and measurement conventions can obscure the continuity of faults from one country to another and make rapid post-event analysis challenging. “As far as I understand, the continuation of the Ravian fault is called the Başkale Fault on the Turkish side,” says Eyidoğan, a professor at Istanbul Technical University. “Can we propose that the Goharan Fault in Iran is the continuation of the Saray Fault on the Turkish side?” he suggests.

A region at risk of damaging earthquakes

Earthquakes along strike-slip faults, like those that exist throughout this region, tend to have lower magnitudes than those at convergent margins, but these can still be quite large. The Başkale Fault is capable of producing a magnitude-7 earthquake, for example (Emre et al., 2016). In fact, in 1930 there was a magnitude-7.1 within the same region, on the Salmas Fault parallel to the Goharan–Saray Fault.

The proximity of the 1930 earthquake and this recent cluster “is important in terms of the energy accumulation in the area, the interaction between the seismogenic sources, and the possible maximum magnitudes for seismic hazard assessments,” notes Farnaz Kamranzad, a seismologist at the University of Tehran. She suggests that this earthquake cluster is similar to an event that occurred in the area in 2012, noting that “moderate earthquakes are quite frequent in the northwest part of Iran.”

The two recent earthquakes of February 23 were particularly destructive for their size. This is because they occurred at shallow depths—about 10 km for both. The closer to the surface an earthquake nucleates, the less energy dissipates before it reaches the surface, and therefore the more shaking that occurs.

Knowing the potential for destruction during earthquakes is integral to preparing regions for shaking hazards. Turkey’s most recent earthquake hazard map, published in 2018, indicates that the Başkale fault is capable of generating a magnitude-7 temblor. Despite this warning, this cluster of earthquakes from February, as well as the January earthquake about 500 km to the west on a different fault system, “showed us how unprepared the settlements are for earthquake risks,” says Eyidoğan. He adds, “We are sadly watching how the stone masonry and adobe masonry structures in rural areas are weak, and the so-called reinforced concrete carcass multi-story buildings are demolished in cities.” It is clear that more work is to be done to understand the geology in this region, to better prepare citizens of both countries for future damaging earthquakes.

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 Eos: “Fluid Pressure Changes Grease Cascadia’s Slow Aseismic Earthquakes”

From AGU

From Eos

2.18.20
Mary Caperton Morton

Twenty-five years’ worth of data allows scientists to suss out subtle signals deep in subduction zones.

Cascadia subduction zone

Cascadia plate zones

The study region followed the coast of Vancouver Island in British Columbia, one of the source regions for slow earthquakes along the Cascadia Subduction Zone. Credit: NASA

Not all earthquakes make waves. During slow “aseismic” earthquakes, tectonic plates deep in subduction zones can slide past one another for days or even months without producing seismic waves. Why some subduction zones produce devastating earthquakes and tsunamis while others move benignly remains a mystery. Now a new study is shedding light on the behavior of fluids in faults before and after slow-slip events in the Cascadia Subduction Zone.

Aseismic earthquakes, also known as episodic tremor and slip, were discovered about 20 years ago in the Cascadia Subduction Zone, where oceanic plates are descending beneath the North American plate at a rate of about 40 millimeters per year.

Vancouver profile

Oregon profile

This 1,000-kilometer-long fault has a dangerous reputation but has not produced a major earthquake since the magnitude 9.0 megathrust earthquake and tsunami that struck on 26 January 1700. Scientists think that some of Cascadia’s energy may be dissipated by regular aseismic events that take place deep in the fault zone roughly every 14 months.

Episodic tremor and slip occur deep in subduction zones, and previous studies have suggested that these slow-slip events may be lubricated by highly pressurized fluids. “There are many sources of fluids in subduction zones. They can be brought down by the descending plate, or they can be generated as the downgoing plate undergoes metamorphic reactions,” said Pascal Audet, a geophysicist at the University of Ottawa in Ontario and an author on the new study, published in Science Advances.

“At depths of 40 kilometers, the pressure exerted on the rocks is very high, which normally tends to drive fluids out, like squeezing a sponge,” Audet said. “However, these fluids are trapped within the rocks and are virtually incompressible. This means that fluid pressures increase dramatically, weakening the rocks and generating slow earthquakes.”

This 1,000-kilometer-long fault has a dangerous reputation but has not produced a major earthquake since the magnitude 9.0 megathrust earthquake and tsunami that struck on 26 January 1700. Scientists think that some of Cascadia’s energy may be dissipated by regular aseismic events that take place deep in the fault zone roughly every 14 months.

Eavesdropping on Slow Quakes

To study how fluid pressures change during slow earthquakes, lead author Jeremy Gosselin, also at Ottawa, and Audet and colleagues drew upon 25 years of seismic data, spanning 21 slow-earthquake events along the Cascadia Subduction Zone. “By stacking 25 years of data, we were able to detect slight changes in the seismic velocities of the waves as they travel through the layers of oceanic crust associated with slow earthquakes,” Audet said. “We interpret these changes as direct evidence that pore fluid pressures fluctuate during slow earthquakes.”

Audet and colleagues are still working to identify the cause and effect of the pore fluid pressure changes. “Is the change in fluid pressure a consequence of the slow earthquake? Or is it the opposite: Does an increase in pore fluid pressure somehow trigger the slow earthquake? That’s the next big question we’d like to tackle.”

“I’m surprised and impressed they were able to isolate these signals,” said Michael Bostock, a geophysicist at the University of British Columbia in Vancouver who was not involved in the new study. “They’re very subtle, but they’re all pointing in the same direction.”

Theoretical models, as well as other seismic studies on subduction zones in Japan and New Zealand, have offered supporting lines of evidence that pore fluids are redistributed at the boundaries of tectonic plates during slow-slip events, Audet said. “Other studies have offered somewhat indirect evidence for this idea, but our study offers the first direct evidence that fluid pressures do in fact fluctuate during slow earthquakes.”

The next steps will be to conduct similar seismic studies on other subduction zones, Bostock said. It’s too soon to say whether this fluid behavior is universal to all slow-earthquake zones, but “there may be other factors at play as well, such as temperature and pressure, that create a sweet spot where slow earthquakes are more likely to occur,” he said. The right combination of overlapping factors may help explain why some fault zones record more aseismic events than others.

Whether these changes in fluid pressures could be used to predict where and when a slow-slip event might occur is unknown, Bostock said, although “slow earthquakes are already more predictable than regular earthquakes.” In Cascadia, for example, they’re known to occur about every 14 months, give or take, for reasons that remain unclear. “Prediction is the holy grail of earthquake science, but it’s fraught with difficulties. Tectonic faults, despite their grand scale, are very sensitive to perturbations in ways we don’t clearly understand yet.”

See the full article here .

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

Please help promote STEM in your local schools.

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 temblor: “Past meets present to help future seismic hazard forecasts in San Diego, CA”

From temblor

January 13, 2020
Alka Tripathy-Lang
@DrAlkaTrip

Urbanization obscures a complex fault zone on which downtown San Diego sits, but decades-old geotechnical studies reveal the faults.

Urbanization in downtown San Diego. Credit: Tony Webster CC-BY-2.0.

Fault studies often rely on surface expressions of the ground’s movement. In densely populated urban areas, such as San Diego, this evidence is concealed beneath the cityscape. Now, though, a team has used historical reports to trace faults through downtown San Diego in unprecedented detail, establishing a template that other fault-prone cities can follow to illuminate otherwise hidden hazards.

Urbanization obscures geology

Downtown San Diego, popular for its beaches and parks, also hosts the active Rose Canyon Fault Zone, a complex hazard that underlies the city from northwest of La Jolla through downtown, before curving into San Diego Bay.

Rose Canyon Fault. https://www.nbcsandiego.com/

Like the nearby San Andreas, the Rose Canyon Fault is right-lateral, meaning if you were to stand on one side, the opposite side would appear to move to your right. But it plods along at a rate of 1-2 millimeters per year, unlike its speedy neighbor, which indicates a comparatively lower seismic risk.

“We haven’t had a major rupture” on the Rose Canyon Fault since people have been living atop it, says Jillian Maloney, a geophysicist at San Diego State University and co-author of the new study. So it’s hard to say what kind of damage would be caused, she says. “But, a magnitude-6.9 [of which this fault is capable] is big.”

Because of urbanization, though, “there haven’t been any comprehensive geologic investigations” of the faults underlying downtown San Diego, Maloney says. This presents a problem because detailed knowledge of active and inactive fault locations, especially in a complicated area where the fault zone bends, is key for successful seismic hazard assessments, she says. The state and federal government maintain fault maps and databases, but their accuracy at the small scale was unknown.

Map of the Rose Canyon Fault near San Diego, California, USA. USGS

Faded pages

A solution to the lack of detailed fault mapping in downtown San Diego resided in decades of old geotechnical reports. These individual studies the size of a city block or smaller are required by the city for any proposed development near active faults, as mapped by the state. Although the data are public once the reports are filed with the city, the reports had not been integrated into a comprehensive or digital resource, and the city does not maintain a list of such reports.

This bird’s-eye view of downtown San Diego was drawn by Eli Glover in 1876. Prior to the development of downtown San Diego, the Rose Canyon Fault Zone was expressed on the surface and could be seen laterally offsetting topographic features. Credit: Library of Congress, Geography and Map Division.

According to Luke Weidman, lead author of this study, which was his master’s project, the first challenge was determining how many reports were even available. Weidman, currently a geologist at geotech firm Geocon, went straight to the source: He asked several of San Diego’s large geotechnical firms for their old publicly available reports in exchange for digitizing them. 


Weidman scrutinized more than 400 reports he received, dating from 1979 to 2016. Many were uninterpretable because of faded or illegible pages. He assembled the 268 most legible ones into a fault map and database of downtown San Diego. Because reports lacked geographical coordinates, Weidman resorted to property boundaries, building locations, park benches and even trees to locate the reports on a modern map, says Maloney, one of his master’s advisors. Weidman, Maloney and geologist Tom Rockwell also of San Diego State published the findings from their comprehensive interactive digital map last month in Geosphere, along with an analysis of the Rose Canyon Fault Zone in downtown San Diego.

Below from https://pubs.geoscienceworld.org/

Map of the Rose Canyon fault zone (RCFZ) through San Diego (SD), California (USA) and across the San Diego Bay pull-apart basin. Black box shows the extent of Figure 3. Grid shows population count per grid cell (∼1 km2) (source: LandScan 2017, Oak Ridge National Laboratory, UT-Battelle, LLC, https://landscan.ornl.gov/). DF—Descanso fault; SBF—Spanish Bight fault; CF—Coronado fault; SSF—Silver Strand fault; LNFZ—La Nacion fault zone.

Street map of greater downtown San Diego region showing Alquist-Priolo (AP) zones and faults from the U.S. Geological Survey (USGS) fault database (USGS-CGS, 2006). Black box shows the extent of Figures 6, 7, and 8. Background imagery: ESRI, HERE (https://www.here.com/strategic-partners/esri), Garmin, OpenStreetMap contributors, and the GIS community.

Fault findings

The team found that downtown San Diego’s active faults—defined in their paper as having ruptured within the past 11,500 years—largely track the state’s active fault maps. However, at the scale of the one-block investigations, they found several faults mapped in the wrong location, and cases of no fault where one was expected. Further, the team uncovered three active faults that were not included in the state or federal maps. At the scale at which geotechnical firms, government, owners and developers need to know active fault locations, the use of this type of data is important, says Diane Murbach, an engineering geologist at Murbach Geotech who was not involved in this study.

This map of downtown San Diego, Calif., shows fault locations as mapped by the U.S. Geological Survey (USGS), and faults as located by the individual geotechnical reports compiled in the new study. Green, light orange, dark orange and red boxes indicate whether individual geotechnical studies found no hazard (green), active faults (red) or potential fault hazards (dark or light orange). Note that the Rose Canyon Fault Zone as mapped by USGS occasionally intersects green boxes, indicating the fault may be mislocated. Where the fault is active, mismatches exist as well. Note the arrow pointing to the ‘USGS-Geotech fault difference,’ highlighting a significant discrepancy in where the fault was previously mapped, versus where it lies. Credit: Weidman et al., [2019].

Maloney says they also found other faults that haven’t ruptured in the last 11,500 years. This is important, she says, because “you could have a scenario where an active zone ruptures and propagates to [one] that was previously considered inactive.”

This research “is the first of its kind that I know of that takes all these different reports from different scales with no set format, and fits them into one [usable] database,” says Nicolas Barth, a geologist at the University of California, Riverside who was not part of this study. Many cities have been built on active faults, obscuring hints of past seismicity, he notes. “This is a nice template for others to use,” he says, “not just in California, but globally.”

References
Weidman, L., Maloney, J.M., and Rockwell, T.K. (2019). Geotechnical data synthesis for GIS-based analysis of fault zone geometry and hazard in an urban environment. Geosphere, v.15, 1999-2017. doi:10.1130/GES02098.1

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 EarthSky: “Magnitude 6.4 earthquake shakes Puerto Rico”

From EarthSky

January 7, 2020
Deborah Byrd

USGS reports that the strong earthquake in Puerto Rico this morning was “widely felt.” Strong to very strong shaking occurred across parts of southern Puerto Rico closest to the event, and moderate shaking occurred across the rest of the island.

The January 7, 2020 6.4-magnitude earthquake in Puerto Rico was centered south of the island. Image via USGS.

On January 7, 2020, a magnitude 6.4 earthquake struck Puerto Rico at 4:24 a.m. local time (08:24:26 UTC). Significant damage is possible. Over the past several weeks, hundreds of small earthquakes have occurred in the Puerto Rico region, beginning in earnest with a magnitude 4.7 earthquake late on December 28 and a magnitude 5.0 event a few hours later.

The magnitude 6.4 earthquake on January 7 was widely felt. According to ShakeMap, strong to very strong shaking occurred across parts of southern Puerto Rico, closest to the event, and moderate shaking occurred across the rest of the island. The NOAA Tsunami Warning System states no tsunami warning or advisory. The USGS summary page on this earthquake includes an aftershock forecast. Aftershocks will continue near the mainshock.

Since the magnitude 4.7 event on December 28, over 400 M 2+ earthquakes have occurred in this region, ten of which were magnitude 4+, including the January 7, 2020, 6.4 event and a January 6, 2020 5.8 quake. The preliminary location of the January 7 6.4 earthquake is within about 7.5 miles (12 km) of the January 6, 2020, magnitude 5.8 earthquake. The proximity of these events to Puerto Rico, and their shallow depth, mean that dozens of these events have been felt on land, though with the exception of the latest two earthquakes, the magnitude 6.4 and the magnitude 5.8, none are likely to have caused significant damage.

The January 6 and 7, 2020, magnitude 5.8 and magnitude 6.4 earthquakes offshore of southwest Puerto Rico occurred as the result of oblique strike slip faulting at shallow depth. At the location of this event, the North America plate converges with the Caribbean plate at a rate of about 20 mm/yr towards the west-southwest. The location and style of faulting for the event is consistent with an intraplate tectonic setting within the upper crust of the Caribbean plate, rather than on the plate boundary between the two plates.

Tectonics in Puerto Rico are dominated by the convergence between the North America and Caribbean plates, with the island being squeezed between the two.

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

To the north of Puerto Rico, North America subducts beneath the Caribbean plate along the Puerto Rico trench. To the south of the island, and south of today’s earthquake, Caribbean plate upper crust subducts beneath Puerto Rico at the Muertos Trough. The January 6 earthquake, and other recent nearby events, are occurring in the offshore deformation zone bound by the Punta Montalva Fault on land and the Guayanilla Canyon offshore.

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

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

Stem Education Coalition

Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

From Nature: “Two of the biggest US earthquake faults might be linked”

From Nature

05 December 2019

The earthquake that devastated San Francisco, California, in 1906 arose from the San Andreas fault — which might be linked to another major fault zone to the north.Credit: Underwood Archives/Getty

Two of North America’s most fearsome earthquake zones could be linked.

A controversial study argues that at least eight times in the past 3,000 years, quakes made a one–two punch off the west coast of the United States. A quake hit the Cascadia fault off the coast of northern California, triggering a second quake on the San Andreas fault just to the south. In some cases, the delay between the quakes may have been decades long.

The study suggests that Cascadia, which scientists think is capable of unleashing a magnitude-9 earthquake at any time, could set off quakes on the northern San Andreas, which runs under the San Francisco Bay Area.

Several earthquake scientists told Nature that more work is needed to confirm the provocative idea. Researchers have long considered the two faults seismically separate.

Chris Goldfinger, a geologist and palaeoseismologist at Oregon State University in Corvallis, will present the findings on 13 December at a meeting of the American Geophysical Union in San Francisco. “This is mostly a circumstantial case,” he says. “I don’t have a smoking gun.”

Tantalizing clues

Goldfinger and his colleagues first suggested in 2008 that earthquakes in the southern part of Cascadia could trigger quakes on the northern San Andreas [1]. The scientists reported finding layers of churned-up, sandy sediment in sea-floor cores drilled offshore. These layers, called turbidites, usually form when earthquakes shake the sea floor, causing underwater landslides. The researchers reported finding turbidites in Cascadia that seemed to form just before similar turbidites near the San Andreas — perhaps as a Cascadia quake triggered a San Andreas one.

But it was hard to pinpoint exactly when the turbidites had formed, and Goldfinger knew he needed more evidence. “So that’s what we did,” he says. “We went out and got more cores.”

Now he has data from seven cores drilled offshore in southern Cascadia and seven cores drilled near the northern San Andreas. The two sites are around 100 kilometres apart — close enough to feel shaking from both faults.

At eight places in both sets of cores, Goldfinger spotted unusual, two-layered turbidites and realized that they were telling him something new. “Finally the lights went on for me,” he says. The two-layered turbidite “has to be two quakes recorded together”.

Doubts remain

As Goldfinger sees it, a Cascadia quake shook the coastline first, causing landslides that show up in both sets of cores as the first layer of turbidites. Then, at some later point, the northern San Andreas also shook, causing the second turbidite layer to form.

“This story is pretty convincing,” says Jason Patton, an engineering geologist with the California Geological Survey in Sacramento who was a co-author on the 2008 paper. “Cascadia turbidites are covered by San Andreas turbidites, so the Cascadia turbidites were deposited first.”

Others are reserving judgement. Turbidites show that the ground shook at some point in the past, but it’s difficult to tell exactly when or where those quakes happened, says Joan Gomberg, a seismologist at the US Geological Survey in Seattle, Washington. “All this uncertainty leaves multiple, equally plausible interpretations on the table — most of which are not sensational,” she says. For instance, the turbidites could have been formed by unrelated quakes happening anywhere across the seismically active Pacific Northwest.

Ross Stein, a seismologist with the earthquake-preparedness firm Temblor in Redwood City, California, wants to see detailed modelling of how stress from the Cascadia fault might be transferred to the northern San Andreas. Researchers generally agree that a large earthquake can sometimes trigger another on a nearby fault, by transferring stress and bringing the second fault closer to failure. But it’s not clear whether that might happen between southern Cascadia and the northern San Andreas, Stein says.

Next week at the conference, Goldfinger says, “I’m just going to lay out the case.”

References

1.

Goldfinger, C. et al. Bull. Seismol. Soc. Am. 98, 861–889 (2008).

See the full article here .

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

Please help promote STEM in your local schools.

Stem Education Coalition

Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.