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Quake Early Warning Network Adds Sensors

The new sensors augment the West Coast ShakeAlert network, a collaboration between the U.S. Geological Survey and universities in California and the other coastal states.

Ground motion sensors buried 9 feet underground atop Mount Burdell late last month are now part of an early warning system that will give cellphone users and others precious extra seconds to prepare for the next big earthquake.

The University of California’s Berkeley Seismological Laboratory installed the sensors with the permission of the Buck Institute for Research on Aging, which owns the land.

“We love helping other scientists, especially those who are providing a valuable resource to help all of us be safe in the event of an earthquake,” said Buck Institute spokeswoman Kris Rebillot.

The early warning system, known as ShakeAlert, is a collaborative effort involving the University of California, Berkeley, the California Institute of Technology, the University of Washington, the University of Oregon, the U.S. Geological Survey and state agencies. So far, Congress has appropriated nearly $162 million to help create the system and the state of California has provided more than $58 million.

ShakeAlert planners seek to place 1,675 sensor stations in California, Oregon and Washington.

“We are targeting a certain distance between each station so we have a nice spread-out, dense network,” said Jennifer Strauss, a spokeswoman for the Berkeley Seismological Laboratory. “We are about 80 percent built out and fully funded to complete the rest of the work.”

Strauss said there are already about 20 sensor stations installed throughout Marin, but the U.S. Geological Survey is still eager to find sites for two more stations near Tomales.

The system works by detecting the first energy that radiates from an earthquake. This primary, or “p” wave, energy rarely causes damage. Data is relayed from the motion sensors to data processing centers, where an algorithm that was developed with the help of the Berkeley Seismological Laboratory estimates the strength of the quake and forecasts the areas that will likely feel shaking.

If the quake is judged to be large enough to be consequential, the information gets sent to ShakeAlert’s partners. These include Google, which sends out an alert to Android users, and the operators of the MyShake app, which provides alerts to others, including iPhone users. The MyShake app is funded by the California Governor’s Office of Emergency Services.

The cellphone app warnings are triggered in response to magnitude 4.5 earthquakes and greater. Wireless emergency alerts, similar to “Amber alerts,” are used in response to earthquakes greater than a 5.0 magnitude.

ShakeAlert, which is similar to early warning systems in Mexico and Japan, began issuing alerts in California in 2019 and in Oregon in March 2021. The most recent alert was issued via cellphones on July 14 when a magnitude 4.6 quake struck about 8 miles northeast of Ridgecrest in Kern County.

The system sends information on quakes magnitude 3.5 and greater to other ShakeAlert partners such as the Bay Area Rapid Transit and MetroLink mass transit systems. BART responds to ShakeAlert alerts by automatically slowing trains when an earthquake occurs.

Other ShakeAlert partners receiving information include companies such as Early Warning Labs, Everbridge and Global Security Systems, which operates Alert FM. Strauss said these entities decide for themselves how large a quake needs to be to issue an alert to their customers.

How much advance notice people receive via the ShakeAlert system will depend on how far away they are from the epicenter of the quake.

“For people or infrastructure directly at the epicenter, they’re not likely to get an early warning. They’re right in the thick of it,” Strauss said. “Further away from the epicenter, now we have an opportunity to start outrunning the seismic waves with our communications. You’re not likely to get several minutes of warning. We tend to talk in scales of seconds and tens of seconds.”

The system’s designers, however, note that even a few extra seconds can help people to avoid injury and allow corporations and institutions to protect their equipment.

For example, it’s enough time for people to duck, cover and hold, or even seek shelter under a sturdy table, away from falling hazards such as bookcases, ceiling lights and fixtures. More than half of the injuries sustained during the 1994 Northridge earthquake were caused by people falling.

Businesses and government entities can use automated control systems to isolate hazardous chemicals, turn off dangerous machinery, start emergency generators or move data to safe storage.

Strauss said if people use the few seconds warning they receive it will reduce their chance of injury, but she cautioned that people must be prepared to respond immediately.

“If it’s not part of your training that you practice, then you might not be as prepared as you think you are when the event strikes,” she said. “So make it part of your preparedness drills.”

©2022 The Marin Independent Journal. Distributed by Tribune Content Agency, LLC.