From temblor: “The Whistle: Are We Ready for the Big One?”


From temblor

October 24, 2018

Jason R. Patton, Ph.D.
Ross Stein, Ph.D.
Volkan Sevilgen, M.Sc.

It Has Happened Before

The southern San Andreas fault (SSAF) is a plate boundary strike-slip fault, where the Pacific plate moves northward relative to the North America plate. There have been large earthquakes on this fault in historic time, including the 1857 Forth Tejon earthquake. This 1857 earthquake is estimated to have been a magnitude 7.9 earthquake (larger than the recent earthquake in Sulawesi, Indonesia). There is also a record of prehistoric earthquakes on this fault, spanning the past 5000 years (Weldon et al., 2004; Sharer et al., 2007). These authors have determined that the average time between earthquakes on the SSAF is 105 years. However, the time between earthquakes ranges from 31 – 165 years. This large variation in inter-event time periods makes it more difficult to know when the next “Big One” will happen.

The USGS prepares earthquake scenarios based on our knowledge about past earthquakes and how future earthquakes may behave based on our empirical knowledge. Below is a USGS scenario map for the part of the SSAF that ruptured in the 1857 Fort Tejon earthquake. The color scale represent relative earthquake shaking intensity based on the Modified Mercalli Intensity scale. Warmer colors represent areas of stronger ground shaking. While the map below is based on a computer model, this is a good estimate of how strongly the ground shook in 1957. Note how the strongest ground shaking is adjacent to the fault.

USGS Shakemap scenario map for the southern San Andreas fault, showing an estimate of shaking intensity from an earthquake similar in length and magnitude to the 1857 Fort Tejon earthquake. The part of the fault that slips in this scenario earthquake is shown as a black line, very similar to the known extent of the 1857 earthquake.

Several governments and non-governmental organizations prepare estimates of seismic hazard so that people can ensure their building codes are designed to mitigate these hazards. The Global Earthquake Model (GEM) is an example of our efforts to estimate seismic hazards on a global scale. uses the Global Earth Activity Rate (GEAR) model to provide estimates of seismic hazard at a global to local scale (Bird et al., 2015). GEAR blends quakes during the past 41 years with strain of the Earth’s crust as measured using Global Positioning System (GPS) observations.

Below is a map prepared using the app. Seismicity from the past month, week, and day are shown as colored circles. The temblor app suggests that this region of San Bernardino, CA has an earthquake score of 93. To find out what your earthquake score is, enter your address in the app at

Earthquake Risk map for southern California, centered on the inland empire. Active faults are shown as red lines. Earthquakes from the past month are shown as circles.

We Imagine the Consequences

Earthquakes can cause damage to buildings and other infrastructure due to the shaking intensity. The closer to the earthquake, the higher the intensity. Buildings are located on different types of bedrock and this can amplify the shaking intensity in places. How do we know this? We have made direct observations of the damage from earthquakes.

There is ample evidence of what happens during earthquakes like what will occur on the SSAF someday. The same fault system, further north, has also ruptured in historic time. In 1868, the Hayward fault (a sister fault of the San Andreas) had an earthquake that caused extensive damage in the San Francisco Bay area. The USGS and the California Geological Survey are using the 150 year anniversary of this earthquake as a tool to educate the public about earthquake hazards along these active faults in northern California. Here is a short video about the HayWired Scenario. More can be learned about how to outsmart disaster at the “HayWired” website here.

Below is a photo from the aftermath of the 1868 Hayward fault earthquake.

This photo shows damage to “Pierce’s House,” a building damaged by the 1868 Hayward fault earthquake. Image source: Wikimedia Commons, public domain.

Another historic earthquake that caused extensive damage in California is the 1906 Great San Francisco earthquake, another San Andreas fault earthquake. The damage from this earthquake included building damage and fire. Fire is one of the most common damaging effects of an earthquake like what will happen someday on the SSAF.

Below is a photo showing damage to houses that were built on material that did not perform well during an earthquake.

Photo of houses following the 1906 San Francisco earthquake. Photo from National Archives Record Group 46, public domain.

The combination of hazard and exposure (people) is what we call risk. When people are exposed to earthquake hazards, they are at risk from damage due to those earthquakes. If there is an earthquake and nobody is there to experience the earthquake, there is no risk. One major difference between 1868, 1906, and today is that there are more people that live close to these earthquake faults. While the average number of earthquakes stays relatively constant through time, as the population grows in earthquake country, the risk also grows.

Do you live along the San Andreas or some other plate boundary fault? What about another kind of fault?

To learn more about your exposure to these hazards, visit

When is the next Big One?

We don’t know when the next southern San Andreas fault big earthquake will happen. Currently there are no scientifically demonstrated ways to predict earthquakes. We can use the frequency of past earthquakes and patterns of earthquake occurrence (current seismicity) to estimate the chance that an earthquake will occur over a period of time.

These estimates of future earthquake occurrence are called forecasts. Most people are familiar with weather forecasts, but we know much less about earthquakes than we do about weather. Because of this, earthquake forecasts may not have the same amount of accuracy that weather forecasts do. However, these forecasts are based on the latest cutting edge science about earthquakes and are monumentally better than simply tossing a coin. The cool thing about these forecasts is that the science behind them improves over time as we learn more about how earthquakes happen. This is another improvement over coin tosses, which flip pretty much the same as they did since coins were invented.

The Whistle is an upcoming series of broadcasts produced by the Empire Network, a collaboration between KVCR, PBS, and National Public Radio.

This four-part documentary series that dives into earthquake science, history, local and international earthquakes and tsunamis, California preparedness and immediate response, prevention, mitigation, retrofits, resilience, sustainability, conservation, incentives, challenges, new technologies… and solutions. Are we ready for the Big One?

The first episode airs on October 25 and we will learn about earthquakes and the San Andreas fault:

Earthquakes and the San Andreas fault. The Ring of Fire. What do we know about earthquakes today? What causes them, how often, why we know the Big One is due. Evolution of seismology and our understanding of earthquakes and plate tectonics. How did the First Nations and early European settlers deal with Earthquakes before modern technology? How dangerous is the threat and how much of an impact can a big earthquake cause? What will happen when the next big one hits?

Episode 2 covers how our immediate response might unfold during and following the Big One. Episode 3 reviews our knowledge of the current state of infrastructures (buildings, roads) and how an earthquake might impact these investments in society. Finally, the 4th episode presents an evaluation of how we have improved our ability to be resilient in the face of disasters from the Big One following decades of applying the scientific method to our observations of earthquakes. How will Earthquake Early Warning work and how will we benefit from this? Learn more by watching The Whistle.

The premiere for “The Whistle, Are We Ready for the Big One?” premieres on Thursday Oct. 25. Watch the first episode on television, or head to this website where the video will be available to stream online.



Bird, P., Jackson, D. D., Kagan, Y. Y., Kreemer, C., and Stein, R. S., 2015. GEAR1: A global earthquake activity rate model constructed from geodetic strain rates and smoothed seismicity, Bull. Seismol. Soc. Am., v. 105, no. 5, p. 2538–2554, DOI: 10.1785/0120150058

Sharer, K.M., Weldon, R.J.III., Fumal, T.E., and Biasi, G., 2007. Paleoearthquakes on the Southern San Andreas Fault, Wrightwood, California, 3000 to 1500 B.C.: A New Method for Evaluating Paleoseismic Evidence and Earthquake Horizons in Bull. Seismol. Soc. Am., v. 97, no. 4, p. 1054–1093, DOI: 10.1785/0120060137

Weldon, R., Sharer, K.M., Fumal, T., and Biasi, G., 2004. Wrightwood and the Earthquake Cycle: What a Long Recurrence Record Tells Us About How Faults Work in GSA Today, v. 14, no. 9, doi: 10.1130/1052-5173(2004)0142.0.CO;2

See the full article here .


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

QCN bloc

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
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.


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

Learn more about EEW Research

ShakeAlert Fact Sheet

ShakeAlert Implementation Plan