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Earthquake Warning California

As the Emergency Management authority for the State of California, the California Office of Emergency Services (Cal OES) takes a proactive approach to addressing risks, threats, and vulnerabilities to Californians, including earthquakes. The following are responses to frequently asked questions (FAQ) relating to “Earthquake Warning California,” Cal OES’ earthquake early warning program. For more information and the latest updates on Earthquake Warning California, please visit our website: earthquake.ca.gov

What is Earthquake Warning California?

Earthquake Warning California is the name of California’s earthquake warning system. Earthquake Warning California uses the latest technology, including smartphone applications and Wireless Emergency Alerts (WEA), to provide individuals with an earthquake warning as soon as shaking is detected by ground motion monitoring in California. Earthquake warnings are designed to provide individuals seconds to take life-saving actions such as to Drop, Cover, and Hold On before shaking is felt. 

How is Earthquake Warning California aiding Californians?

Governor Newsom and the Legislature have made significant investments to fund disaster planning and preparedness – including earthquake early warning alerts. The enacted budget in 2019 included $16.3 million in a one-time General Fund allocation to finish the build-out of the system, including finishing seismic station installation, adding GPS stations to the network, improving telemetry and launching an education campaign. In 2020, the Governor’s budget included an additional allocation of $17.3 million, supported by a one-time loan of the same amount from the School Land Bank Fund, for full operation and maintenance of the system. 

The California EEW System now delivers EEW alerts statewide to the public through three cell-phone-based pathways:  the Cal OES-sponsored MyShake app, Wireless Emergency Alerts (WEA), and to Android-enabled devices. The network of seismic stations that powers EEW alerts in California is nearing completion—all 1,115 stations are either built or funded—so the California EEW Program is now placing greater focus on maintaining the system and seeking adoption of the EEW technology by state and local agencies, businesses, and owners of critical infrastructure throughout the state. Additionally, Cal OES is supporting research to develop additional alerting pathways, including the use of television and radio broadcast signals, to provide widespread and redundant alerting coverage for a variety of public and private-sector use cases. While continuous improvements are ongoing, the system now has a proven track record of providing critical, lifesaving services to the public.

Where are there other earthquake warning systems?

Earthquake-prone countries like Mexico and Japan have long had earthquake early warning systems, with alerts typically delivered through cellphones or public address systems. However, California is the first state in the United States to offer a statewide earthquake early warning system.

When did Cal OES announce Earthquake Warning California?

In October 2019, on the 30th anniversary of the deadly Loma Prieta earthquake, Governor Newsom announced the launch of the nation’s first statewide Earthquake Early Warning System, which married the new smartphone application dubbed “MyShake” with traditional alert and warning delivery methods such as Wireless Emergency Alerts (WEA). In August 2020, Cal OES unveiled the new name for the program — Earthquake Warning California.

How does the system work?

During an earthquake, a rupturing fault sends out different types of seismic waves. The fast-moving primary waves (P-waves) are the first to arrive, but the damage is generally caused by the slower secondary waves (S-waves) and surface waves. Sensors detect the P-wave and immediately transmit data to an earthquake warning center where the location and size of the quake are determined and updated as more data becomes available. A ShakeAlert® Message from the warning center is quickly made available to distribution partners including MyShake, Google, and WEA who deliver alerts to the public.

How much time will people receive and what can they do in that period of time?

Warnings can provide seconds to take action. Even a few seconds of advance notice can be lifesaving. At a minimum, these rapid response warnings will allow users to drop, cover, and hold on during an earthquake.

What is the MyShake App?

The MyShake App is an earthquake warning tool developed by UC Berkeley, in partnership with USGS ShakeAlert and Cal OES. The MyShake App sends a warning to smartphone users that have installed the app in the vicinity of an earthquake as soon as ground sensors detect significant shaking. MyShake App users must enable location services on their mobile devices in order to receive earthquake warnings, since the technology only notifies users in the immediate area when shaking occurs. The app is available for mobile devices at no cost through the Google Play store and Apple App store.

How does the MyShake App work?

The MyShake App uses existing smartphone technology to both detect earthquakes and issue alerts. Additionally, MyShake collects data using the onboard accelerometers on all phones for research to improve the system in the future. The MyShake App aims to form a partnership between the seismology research community and the general public with the goal to mitigate the impacts of earthquakes. The MyShake App achieves this goal by turning smartphones into sensors to collect earthquake data and deliver that earthquake data to users as a warning (no personal data is collected in this process).

How does the system detect earthquakes?

There are over 900 sensors positioned across the state that can detect earthquakes primary waves of earthquakes and more are on the way. When an earthquake triggers sensors, that data is then sent to processing centers to locate the earthquake, determine the magnitude, and the estimated shaking. This data (called a ShakeAlert® Message) is sent to MyShake, Google, and WEA who deliver alerts to the public. MyShake users who receive an earthquake warning can share input with MyShake that they did or did not feel the earthquake. MyShake scientists can use this data to better understand earthquakes and develop and improve earthquake early warning technologies.

Does the app allow users to customize notifications for specific locations?

Yes. Currently this is a feature on the Android version where users can set up to three locations with control over the mile coverage and earthquake magnitude. We’re hoping for iPhones to have this feature in the future.  Alternatively, you also have the option to set a default HomeBase. That way no matter where you happen to be, even if your location services are turned off, you can receive an early warning alert at your HomeBase.

Keep in mind that alerts will only go to your device if either your phone location or your chosen HomeBase is in the affected area. MyShake will not be able to alert you when location services are turned off if your current location is outside of your HomeBase area and an alert is headed to your current location.

What is the difference between MyShake warning notifications and alerts and WEA alerts?

Alerts are automatically delivered to areas that could experience weak shaking or greater. Users must enable location services on their phone to receive earthquake alerts. When an alert is received depends on the distance an individual or business is from the epicenter of the earthquake. The closer the user, the shorter the warning time; the further they are, the longer the warning time they will generally receive.

FEMA’s Wireless Emergency Alert (WEA) system operates nationwide and delivers text-like messages that are shared with WEA-capable mobile devices during emergency situations. The WEA system delivers a variety of alerts for America’s Missing Amber, national emergencies, wildfires, earthquakes (currently only in California), and imminent threats. For earthquakes, Californians may receive ShakeAlert® powered alerts from MyShake, Google, and WEA. However, WEAs will only be sent to individuals who could feel light shaking or greater for earthquakes magnitude 4.5 or greater. To maximize the chances of getting an earthquake alert Californians are recommended to download the MyShake App in addition to the other ways of getting alerts.

What are the benefits of these warnings?

A few seconds of warning can provide life-saving opportunities. With a large earthquake, serious shaking can knock individuals to the ground or result in building damage and injuries.

Public Warning – Gives Californians the opportunity to take protective actions such as “Drop, Cover, and Hold On” and to turn off utilities such as water, electricity, and gas. 

First Responder Mobilization – Opens fire station doors for rapid deployment of emergency response equipment and personnel.

Health Care – Notifies medical providers to stabilize and/or stop delicate procedures and maintain critical medical facility operations.

Utility Infrastructure – Safeguards energy sector grid and other utilities infrastructure for strong shaking with warning alarms and automatic controls to prevent combustions, flooding, and loss of water distribution systems.

Mass Transit – Prevents fatal collisions or derailments by automatically slowing and/or stopping trains, clearing bridges, and diverting inbound airport traffic.

Workplace Safety – Allows employees to take protective actions, initiate elevator recall procedures to ground floor, place sensitive equipment in safe mode, secure hazardous materials, and halt production lines to reduce damage. 

Emergency/ First Responders – Fire stations and paramedics can prepare vehicles and quickly respond to incoming emergencies.

Businesses & Employee Safety — Employees can implement earthquake response plans, prepare for evacuation, and secure important documents.

What other languages is MyShake App available in?

The MyShake App is currently available in English and Spanish, with additional languages coming soon.

How reliable is the MyShake App?

Users may experience false or missed alerts. This can occur when the location or magnitude of an actual earthquake is an error, or when the system records a false ground shaking. Earthquake early warning is a new technology and is constantly being improved. As more Californians download the MyShake App, and report false alerts, the system can be updated and improve future alerts. 

How is Cal OES working with Google and the Android operating system?

Cal OES recently partnered with the U.S. Geological Survey and Google to announce that earthquake alerting technology will automatically be included in millions of Android phones used in California, without the need to download a separate app.  Like MyShake, the new Google technology is designed to potentially provide seconds of warning before the ground starts to shake from a nearby earthquake – enough time to Drop, Cover, and Hold On to help prevent injury.  Warnings are created by seismic sensor data processed at centralized data centers then alerts are delivered to phones by Google through their Android operating system.

How can I become a third-party partner?

We always welcome third-party partners to assist in sharing the message and information on Cal OES’ earthquake warning alert system. We encourage interested individuals, organizations, and businesses to sign up for our monthly toolkit at earthquake.ca.gov

If you are a business or an organization that is interested in Cal OES attending an event or presenting to your organization, please email earthquakeinfo@caloes.ca.gov 

How can I receive more information about earthquake warnings and related resources?

There are a few ways for individuals or organizations to prepare for  an emergency such as earthquake:

  • Download the MyShake App and enable location services to receive earthquake warnings. The app is available for download on Google Play for Android and the Apple Store for iPhone.
  • Have a plan in place in advance so you can act quickly if you receive a MyShake, Android or WEA earthquake warning. Make a plan to DROP, COVER, and HOLD ON in places where you live, work, and play.
  • Visit ca.gov for information and other resources to help prepare for earthquakes in California.
  • Follow Cal OES on social media:
What is the difference between Earthquake Warning California and ShakeAlert?

Earthquake Warning California is the state of California’s earthquake early warning program, which includes staff, earthquake warning tools, as well as education and outreach resources. This program is operated by Cal OES. Earthquake Warning California operates in collaboration with the California Integrated Seismic Network Partners from the: United States Geological Survey (USGS), University of California – Berkeley (UCB), California Institute of Technology (Caltech), and California Geological Survey (CGS). Ground motion sensors and sensors in smartphones are used to detect an earthquake before humans can feel it, these sensors send data to an earthquake alert center, where a ShakeAlert® message is generated and distributed to mobile devices via the MyShake App, Android Earthquake Alerts, and Government Wireless Emergency Alerts (WEA).  

ShakeAlert® is an earthquake early warning (EEW) system operated by the USGS. This system distributes ShakeAlert® messages to Earthquake Warning California tools such as the MyShake App, Android Earthquake Alerts, and WEA.