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

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

ShakeAlert® is an earthquake early warning (EEW) system that detects significant earthquakes so quickly that alerts can reach many people before shaking arrives. ShakeAlert is not earthquake prediction, rather a ShakeAlert Message indicates that an earthquake has begun and shaking is imminent.

What is ShakeAlert? – A short video about ShakeAlert and how it works [4.5 min]. (English or Spanish).

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The U.S. Geological Survey (USGS) along with a coalition of State and university partners implemented Phase 3 of operations of the ShakeAlert® Earthquake Early Warning System for the West Coast of the United States. Many partnerships to utilize ShakeAlert in authentic environments such as utilities, hospitals, transportation systems, and educational environments are active today and more are being developed. In 2022 and beyond, the USGS and its partners will continue to expand these applications in coordination with state agencies in Washington, Oregon, and California.

The primary project partners include:

United States Geological Survey California Governor’s Office of Emergency Services (Cal OES) California Geological Survey California Institute of Technology University of California Berkeley University of Washington University of Oregon ETH Zurich (SED) 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. Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $6.1 billion, with 73% of that figure ($4.5 billion) coming from Washington, Oregon, and California, and 61% ($3.7 billion) from California alone. In the next 30 years, California has a 99.7% chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10% 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 make alerts available for delivery to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the Primary (P) wave energy, which rarely causes damage.

Using P-wave information, ShakeAlert first estimates the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and an alert is made available for delivery to devices that will initiate automated actions and people who will be prompted to take an action such as Drop, Cover, and Hold On. The method can provide warning before the Secondary (S)-wave arrives, bringing the strong shaking that usually causes most of the damage.

Studies in Washington, Oregon, and California have shown that the warning time would range from seconds to tens of seconds. ShakeAlert-powered alerts delivered by alert distribution partners could 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. For every earthquake, there is a region near the epicenter where alerts will not arrive before shaking begins because the ShakeAlert system needs time to detect the earthquake, issue an alert, and for USGS partners to distribute the alert.

ShakeAlert System Goal

The USGS will issue ShakeAlert Messages to facilitate the delivery of public alerts 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 began the testing of public notification in California in October of 2019 through the Wireless Emergency Alert system (WEA) and cell phone apps. ShakeAlert expanded the testing of public alerting to mobile devices to Oregon in March 2021 and Washington in May 2021.

Current Status

In the fall of 2018 the West Coast ShakeAlert system became sufficiently functional and tested to begin Phase 1 of alerting in California, Oregon, and Washington. Several of the 40+ commercial and institutional users are alerting personnel and taking automated actions; an important step in a strategy of phased roll out leading to full public operation.

ShakeAlert partners are working with both public and private mass alert system operators including FEMA, cellular carriers, mass notification companies, and others to provide broader public alerting. The USGS and its partners are working on a comprehensive education and training program to so that the public knows respond to alerts when they are received.

In addition to these Phase 1 implementations, technical improvements to the ShakeAlert system are also part of the story. The sensor network has reached target density in the Los Angeles, San Francisco Bay and Seattle metro regions and version 2.0 of the ShakeAlert production system has been deployed. This version of the ShakeAlert system is produces both point source and line source earthquake solutions, has added ground motion estimation products, and the number of false and missed events has been reduced. ShakeAlert system version 2.0 has also satisfied government cybersecurity requirements and includes improved operational procedures.

The 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 Pacific Northwest Seismic Network (PNSN) and the California Integrated Seismic Network (CISN). CISN is made up of the Southern California Seismic Network (SCSN) and the Northern California Seismic System (NCSS). 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 USGS will develop and operate the ShakeAlert system, and issue public notifications under the authorities of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.