ShakeAlert
[1] As of 2021, the system issues alerts for the country's West Coast (specifically the states of California, Oregon and Washington).
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.
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.
[2][5] In February 2016, the system moved from demonstrable to Production Prototype version 1.0 in California, providing alerts to "pilot" users.
On September 28, 2018, version 2.0 went live,[7][8] allowing the "sufficiently functional and tested" system to begin Phase 1 of alerting California, Oregon and Washington.
[10] 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.
[18][needs update] Following the 2020 Salt Lake City earthquake, local media reported that Utah was the next state in line to get ShakeAlert.
[23][24][25][26] 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.
[31][32] Full implementation of ShakeAlert on the West Coast system will require 1,675 seismic stations—1,115 in California and 560 in Oregon and Washington.
[2] During an earthquake, the stations send data to processing infrastructure in monitoring centers which, using various algorithms, are able to calculate the necessary information and generate alerts when needed.
Initially, ShakeAlert processing centers were capable of detecting earthquakes at an early stage because of three specific algorithms.
Lastly, the Virtual Seismologist, known as the VS method, imitated the analysis of a human scientist in terms of capacity, but did so at a faster rate.
[2] In 2024, Global Navigation Satellite System (GNSS) data was added to ShakeAlert to aid in the characterization of large magnitude earthquakes.
[35] The algorithm, GFAST (Geodetic First Approximation of Size and Timing), uses the peak ground displacement recorded at permanent GPS stations to determine magnitude.
GFAST receives initial earthquake source information (origin time and epicenter) from EPIC or FinDer.
ShakeAlert warnings are sent to both institutional users and the general public through a variety of distribution methods; this includes messages via cell phones, television and radio.
These alerts may give people time to take protective actions like "drop, cover and hold on", preventing injuries caused by falling debris.
Bay Area Rapid Transit (BART) was an early user of ShakeAlert, initially connecting to the system in 2012 (when it was still in development).
BART uses the system to automatically brake its trains when shaking threatens the San Francisco Bay Area.
[39] Additional institutional users were able to access alerts from the system, after ShakeAlert version 2.0 went live at the end of September 2018.
Initially the app did not issue alerts, but instead used a phone's accelerometers to record shaking from an earthquake and send the data back to UC Berkeley for analysis, thereby creating a crowdsourced global seismic network.
[46][47] QuakeAlertUSA had been under development (and open to beta users),[48] by Early Warning Labs, LLC, for several years before being publicly released on January 21, 2020 (at which time it only provided earthquake alerts in California).
This app, which only warned of shaking in the Los Angeles County area, was made available to the general public at the end of 2018,[10] but was retired after December 31, 2020.
[55] On August 11, 2020, Google announced that it had partnered with USGS, allowing its Android operating system to distribute ShakeAlerts for California.
[69][70] While mobile apps received the alert, the warning was for an earthquake identified as MW4.8 near Stockton (an incorrect magnitude and location).
