Earthquake - Earthquake early warning system now active in Oregon
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Earthquake

Earthquake early warning system now active in Oregon


Story by Nate Hanson, Keely Chalmers (KGW)

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Published on September 24, 2021 7:13 AM
 
PORTLAND, Oregon. — A much-anticipated warning system aimed at giving people a precious moment to prepare for a massive earthquake is now active in Oregon. The system, called ShakeAlert, is also active in California and is expected to be launched in Washington in May, giving people who live on the West Coast a potentially life-saving tool for when a major earthquake, such as "The Big One," strikes. ShakeAlert was created by the USGS, along with a team of other organizations, to give people a few seconds heads up that an earthquake is happening, and shaking is imminent.

The system is made up of a network of sensors that shares information about the magnitude, location and expected shaking from earthquakes on the West Coast. That information is then sent via cellphones and the internet, according to the USGS.

"ShakeAlert can save lives and reduce injuries by giving people time to take protective actions, such as moving away from hazardous areas and making sure to drop, cover and hold on," the USGS said.

The alerts will be delivered to wireless devices in Oregon starting March 11. Here's a link with...

BACKGROUND

ShakeAlert
ShakeAlert is an earthquake early warning system in the United States, developed and operated by the United States Geological Survey and its partners. As of 2021, the system issues alerts for the country's West Coast . It is expected that the system will be expanded to other seismically active areas of the United States in the future.

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 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 S waves do. These warnings can provide time for persons to take protective actions, such as 'drop, cover and hold on,' 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 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.

Events during system development

2014 California earthquakes

The system issued alerts for several significant southern California earthquakes in 2014 including a MW4.4 event in Encino, a MW4.2 event in Westwood, and a MW5.1 event in La Habra. It also issued a warning 5.4 seconds after the beginning of the MW6.0 South Napa earthquake that hit the Napa region on August 24, 2014. Although it was initially reported that the system provided 10 seconds of warning before the S wave arrived in Berkeley, subsequent information showed that this was in error and the warning arrived only 5 seconds before the S wave in Berkeley. This means the S waves had already arrived in Napa and Vallejo when the warning was issued. San Francisco received 8 seconds warning.

2019 Ridgecrest earthquakes

ShakeAlert generated warnings for both the July 5 MW6.4 and July 5 MW7.1 Ridgecrest earthquakes.

Although not yet publicly available, beta users of the QuakeAlert mobile app received warnings on their phones. On average, the app's beta users received a warning of 45 seconds for both earthquakes. The only publicly available app, ShakeAlertLA, did not send an alert during the earthquakes. According to the City of Los Angeles, the system did not send alerts due to the estimated shaking in the Los Angeles area being below the activation threshold.

Events following general availability

2019 Cholame earthquake

On December 17, 2019, the recently released MyShake app sent its first alert for a MW4.3 earthquake in the Cholame Valley. No Wireless Emergency Alert was transmitted because the magnitude of the earthquake was below the 5.0 threshold.

2021 Antelope Valley earthquake

The 2021 Antelope Valley earthquake occurred in a rural area near the California-Nevada border. Due to the remoteness of the area, there were few sensor stations near the earthquake and this resulted in the MW6.0 earthquake incorrectly being split into 'phantom quakes' by the system–a MW4.8 near Lee Vining, MW4.8 near Stockton, and MW4.3 near Mammoth Lakes. Additionally, it took the system 25 seconds to declare an earthquake and issue an alert. While mobile apps received the alert, the warning was for an earthquake identified as MW4.8 near Stockton . No Wireless Emergency Alert was transmitted because the system initially estimated the magnitude to be below the required MW5.0 threshold .

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