Earthquake Early Warning system

Earthquake early warning (EEW) systems aim to quickly detect earthquakes and alert locations expected to experience significant shaking before the shaking arrives, potentially saving lives and preventing injuries. There are many EEW systems in operation and in development around the world, and the EEW system that is available in the U.S. West Coast states of California, Oregon, and Washington is called the ShakeAlert® system.

The ShakeAlert^® EEW system is operated by the U.S. Geological Survey (USGS) and is a cooperative project between the USGS, state agencies, and university partners including the California Institute of Technology(Caltech), the University of California, Berkeley (UC Berkeley), the University of Washington (UW), and the University of Oregon (UO).

What is the ShakeAlert^® Earthquake Early Warning System?

It is first important to note that earthquake early warning is not earthquake prediction. EEW systems work because the speed of the earthquake’s P-waves is almost twice as fast as the earthquake’s more damaging S-waves, and because the speed of modern telecommunications is many times faster than the speed of seismic waves. This means that an earthquake can be detected by local seismic networks, processed, and alerted on before damaging shaking reaches many locations.

ShakeAlert uses real-time seismic data from local Regional Seismic Networks, such as the SCSN, to rapidly detect the early ground motions of an earthquake in progress. Once ground motion is detected, the data are immediately transmitted to a ShakeAlert processing center, where a complex set of algorithms automatically estimate the earthquake’s location, magnitude, and expected shaking intensity distribution. If the estimated earthquake information meets a set of predetermined criteria, the USGS issues automatic messages to its Technical Partners who rapidly alert people and trigger automated actions. If the initial shaking begins far enough away, the warning time could range from a few seconds to tens of seconds.

ShakeAlert Earthquake Early Warning Basics. During an earthquake, a rupturing fault sends out different types of waves. The fast-moving P-wave is first to arrive, followed by the slower, more damaging, S-wave and later-arriving surface waves. Sensors detect the P-wave and immediately transmit data to a ShakeAlert processing center where the location, size, and estimated shaking distribution of the earthquake are determined. If the earthquake meets the right criteria, a ShakeAlert Message is issued by the USGS. The published ShakeAlert Message is then picked up by delivery partners who produce alerts to notify people to take a protective action such as Drop, Cover, and Hold On and/or trigger an automated action such as slowing a train to prevent derailment.

How can I benefit from the ShakeAlert^® Earthquake Early Warning System?

There are a number of different ways to receive ShakeAlert-powered Alerts on your phone if you are in California, Oregon, and Washington.

If you are in California, you can download and use ShakeAlert-powered EEW mobile phone apps by visiting the Google Play or App Store and searching for “MyShake”, “QuakeAlertUSA”, or “ShakeReadySD”. All apps are available for free and can be easily downloaded and installed on Android and iOS devices. Once the app is installed, you can enable push notifications to receive early warning alerts when an earthquake above a set magnitude is detected in your area. The QuakeAlertUSA app is also available in Oregon, and MyShake is also available in Oregon and Washington.

Android phones have ShakeAlert-powered Alerts built into the operating system. Android operating system alerts are available in California, Oregon, and Washington, and no download is necessary.

ShakeAlert-powered Alerts are also issued via the Wireless Emergency Alert (WEA) system. WEA alerts can reach most modern mobile phones in California, Oregon, and Washington. However, WEA alerts may not be as fast as alerts delivered through other methods, so downloading mobile apps and/or using Android operating system alerts is encouraged.

In addition to alerting cell phones, a number of different Technical Partners have begun pilot testing and implementing ShakeAlert Earthquake Early Warning integrations that make the services they provide safer for the general public. Some examples of automated warning implementation include: slowing trains to prevent derailment; stopping elevators at the nearest floor and opening the doors; opening firehouse doors so they are not stuck shut; throttling water utility valves to prevent emptying of reservoirs; and activating backup generators at hospitals to ensure continued service. Keep an eye on our twitter feed @CaltechSeismo for news releases and highlights when organizations announce new implementation efforts!

Some example applications of the ShakeAlert Earthquake Early Warning System. (Left) Technical partners in the transportation sector may utilize automated systems to slow or stop trains that may be impacted. (Middle) You may receive ShakeAlert messages through one of the approved cell phone apps, Wireless Emergency Alert (WEA) message, or through other means depending on your location and the event magnitude. (Right) Technical partners in the medical field may utilize warning systems to halt procedures or engage backup power in anticipation of potential shaking.

Magnitude and shaking intensity thresholds used to issue ShakeAlert-powered alerts by the different types of alert delivery partners.

How did this all start?

While there had been interest and some early research conducted at Caltech pertaining to earthquake early warning as far back as the 1980’s, those efforts weren’t combined and formalized until the 2000’s. Scientists and engineers at the California Institute of Technology (Caltech), USGS Pasadena, UC Berkeley, the Swiss Federal Institute of Technology (ETH), and the University of Southern California (USC/SCEC) started working on earthquake early warning (EEW) research for California in 2007. This included the development and implementation of an early demonstration EEW system for California, called “CISN ShakeAlert” (Boese et al., 2012). The early ShakeAlert made use of the existing infrastructure of the California Integrated Seismic Network (CISN, Caltech/UC Berkeley/USGS), including real-time waveform data streams from at the time ~380 broadband and strong-motion stations throughout California. Now data streams from more than 1100 stations between California, Oregon, and Washington are being ingested by ShakeAlert to support the ShakeAlert Earthquake Early Warning System on the entire west coast of the US.

Initially, the project was funded through the US Geological Survey (USGS) that also has the formal responsibility of earthquake alerting in the US. In early 2012, the Gordon and Betty Moore Foundation provided three years of new funding for EEW research and development for the west coast of the US. Caltech, UC Berkeley, University of Washington, and USGS used these funds to accelerate EEW research and to improve the ShakeAlert system. In particular, the Moore funding enabled the research and development of new algorithms for creating more accurate warnings for finite-source large (M>7) earthquakes as well as enabling work with early-adopters of ShakeAlert and development of probability-based smart engineering applications. With the USGS spearheading the implementation and management of the ShakeAlert Earthquake Early Warning System, research continues at the Caltech Seismo Lab and other partner institutions to constantly improve warning times, accuracy, and the reliability of the system.

What is the current status of the ShakeAlert^® Earthquake Early Warning System?

As enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2, under the authority of the National Earthquake Hazard Reduction Program, the USGS is in charge of developing, operating, and issuing public notifications through the ShakeAlert system. In 2018, the West Coast ShakeAlert system began Phase 1 of alerting in California, Oregon, and Washington, with more than 40 commercial and institutional users alerting personnel and taking automated actions. The roll-out of public alerts began in 2019, starting first in Los Angeles County in January 2019 and expanding to the entire state of California in October 2019. Public alerts expanded to Oregon in March 2021 and to Washington in May 2021.

The ShakeAlert system is continuously evolving with regular technical improvements and updates. After achieving the target density of seismic stations in major metropolitan areas such as Los Angeles, San Francisco Bay, and Seattle, ShakeAlert system version 2.0 was deployed. This updated version has reduced false and missed event notifications and increased cybersecurity capabilities as required by the US government.

The regional seismic networks (RSNs), including the SCSN, with other partner organizations and institutions involved, continue to expand their seismic networks and research to continuously improve the ShakeAlert Earthquake Early Warning System for the West Coast of the United States.

Where can I learn more?

Visit shakealert.org for more on current efforts, funding and research partners, partnership opportunities, and a comprehensive overview of the West Coast implementation of the ShakeAlert Earthquake Early Warning System.

Information pertaining to the development and implementation of the ShakeAlert^® Earthquake Early Warning System sourced from shakealert.org. Accessed: March 22, 2023.