earth science

ShakeAlert

ShakeAlert is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand ShakeAlert rather than just read about it. In short: ShakeAlert is an earthquake early warning system (EEW) in the United States, developed and operated by the United States Geological Survey (USGS) and its partners. As of 2021, the system issues alerts for the country's West Coast (specifically the states of California, Oregon and Washington).

Key takeaways

ShakeAlert belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect ShakeAlert to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of ShakeAlert from memory before moving on to harder problems.

Reference excerpt

ShakeAlert is an earthquake early warning system (EEW) in the United States, developed and operated by the United States Geological Survey (USGS) and its partners. As of 2021, the system issues alerts for the country's West Coast (specifically the states of California, Oregon and Washington). It is expected that the system will be expanded to other seismically active areas of the United States in the future. ShakeAlert is one of two EEW systems available in the United States, with Google's Android Earthquake Alerts System being the other. Similar to other earthquake early warning systems, ShakeAlert does not predict earthquakes, but rather it attempts to quickly identify a seismic event and issue an alert before widespread shaking is felt. It does this by detecting an earthquake's fast moving (but weak) P waves, then computes the event's location and estimated magnitude, after which it issues the warning. Depending on a person's distance from the earthquake's epicenter, the alert may reach them before the earthquake's slower moving (but destructive) S waves do. These warnings can provide time for persons to take protective actions, such as "drop, cover, and hold," and for organizations to shut down transit systems, equipment, open fire station doors, and trigger specific protocols in hospitals and other sensitive work environments. Research and development of the system began in 2006 and by the fall of 2018, the system was considered "sufficiently functional and tested" to enter phase 1 and begin issuing alerts for the West Coast states. While the warnings are generated by ShakeAlert, USGS does not send the alerts directly, instead relying on various private and public partners to distribute the messages through systems such as Wireless Emergency Alerts (WEA) and mobile apps. A statewide alert distribution system went online in California on October 17, 2019, in Oregon on March 11, 2021, and in Washington on May 4, 2021.

Development

Initially the system has been developed to monitor and alert the West Coast of the United States, an area with significant seismic risk due to the San Andreas fault zone and the Cascadia subduction zone. The West Coast system was developed by a consortium of institutions including the United States Geological Survey, the California Governor's Office of Emergency Services (Cal OES), the California Geological Survey, California Institute of Technology, the Berkeley Seismological Laboratory at University of California, Berkeley, University of Washington, University of Oregon, and the Swiss Federal Institute of Technology in Zürich (ETHZ). Research and development of the West Coast system (initially called CISN ShakeAlert) began in August 2006, becoming demonstrable in August 2009. In 2011, test users (mostly other seismologists) were able to access the system through the "UserDisplay" software. In January 2012, "beta" users were able to access the alerts in California. In February 2015, "beta" users were able to access the alerts in Oregon and Washington. In February 2016, the system moved from demonstrable to Production Prototype version 1.0 in California, providing alerts to "pilot" users. In April 2017, Production Prototype version 1.2 went live, expanding the prototype to Oregon and Washington "pilot" users. (Until this time, the Oregon/Washington system had been developed and operated separately from the California system.) On September 28, 2018, version 2.0 went live, allowing the "sufficiently functional and tested" system to begin Phase 1 of alerting California, Oregon and Washington. Even though ShakeAlert could alert the public beginning in September 2018, the messages themselves could not be distributed until the various private and public distribution partners had completed mobile apps and made changes to various emergency alerting systems. The first publicly available alerting system was the ShakeAlertLA app, released on New Year's Eve 2018 (although it only alerted for shaking in the Los Angeles area). On October 17, 2019—the thirtieth anniversary of the Loma Prieta earthquake—Cal OES announced a statewide rollout of the alert distribution system in California. California refers to their system as the California Earthquake Early Warning System. On March 11, 2021, a statewide alert distribution system was rolled out in Oregon. Rollout of the alert system for the West Coast was completed when a statewide alert distribution system went live in Washington on May 4, 2021.

Future plans Of the 1,675 seismic stations needed for full implementation of the West Coast system, only 1,115 had been built or funded by April 2018 (67% of the total needed). The project continues to solicit property owners for permission to place new seismic stations. Following the 2020 Salt Lake City earthquake, local media reported that Utah was the next state in line to get ShakeAlert.

Funding

In 2014, USGS estimated that the West Coast system would cost $38 million to complete and $16 million per year (equivalent to $50 million and $20 million in 2024, respectively) to operate over and above the investment that had already been made in earthquake monitoring. By 2018, the estimates for the system's cost had grown to $39.4 million for the initial build out and $28.6 million for yearly maintenance and operation (equivalent to $48.3 million and $35.1 million in 2024, respectively). In December 2014, $5 million was added to the USGS budget for ShakeAlert development (equivalent to $10 million in 2024). This enabled USGS to purchase $1 million in seismic instrumentation and award $4 million in funding to the project partners to make the demonstration system more robust. In 2015, more than 30 Congress members signed a joint letter urging the President to add full funding for the system to his federal budget request. The Gordon and Betty Moore Foundation has invested more than $6 million in developing the system.

Neighboring systems In August 2024, the Canadian Earthquake Early Warning system was launched by Natural Resources Canada (NRCan); this system was developed in cooperation with USGS and is based on the same software as ShakeAlert. While the two systems are distinct, USGS and NRCan share processing software, algorithms and real-time data.

Detection methods

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with ShakeAlert

Start with the simplest possible case. Write down what ShakeAlert claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to ShakeAlert before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about ShakeAlert ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of ShakeAlert

In research: ShakeAlert appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses ShakeAlert in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: ShakeAlert is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2019 establishments in California, Earthquake early warning systems, Earthquake engineering, so understanding it makes those chapters shorter.
In everyday life: Look for ShakeAlert outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study ShakeAlert in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what ShakeAlert means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain ShakeAlert out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is ShakeAlert in simple terms?

Why does ShakeAlert matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study ShakeAlert?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on ShakeAlert.