More than 3 million residents got early earthquake warning: ‘A really big success’

Dec. 20, 2022 Updated 11:53 AM PT

More than 3 million people were notified by phone early Tuesday of a 6.4 magnitude earthquake that shook Northern California.

Depending on their distance from the quake’s epicenter — which was about 7.5 miles southwest of Ferndale — many residents were informed of the coming tremors before the shaking began, according to Robert de Groot, part of the U.S. Geological Survey’s ShakeAlert operations team.

About 270,000 users of the MyShake app, which is funded by the California Governor’s Office of Emergency Services, were notified of the earthquake. Most of the 3 million who were notified through Google are Android users who have the alerts preprogrammed into their phone operating system, De Groot said.

The alerts gave users up to 20 seconds to prepare for the earthquake, De Groot said.

“I believe it may be the actual biggest event that we’ve had [for the system] so far,” he said. “The system is doing exactly what it should be. This is actually a really big success for us.”

It takes the ShakeAlert operations team time to detect the event using seismometers that pick up the earthquake as it reaches the surface, then informs a processing center that takes the info and produces it into a data package that can be turned into user-friendly alerts.

People with iPhones may have received alerts even if they do not have an earthquake-detecting app. They could be notified by a Wireless Emergency Alerts system push notification, which is similar to an Amber Alert, De Groot said.

Mark Ghilarducci, director of the California Governor’s Office of Emergency Services, said the early warning system gives residents the opportunity to drop, cover and hold on.

“The system did operate as we had hoped, and [as] we’ve been working to design,” Ghilarducci said.

Like her constituents, Rio Dell Mayor Debra Garnes was jolted awake by the earthquake.

“It was the most intense earthquake that I’ve felt. It was a long duration earthquake, so it was not only significant in size — at 6.4 — it was also long,” the mayor told The Times.

She then had to get to work, coordinating with the city’s building’s department and volunteer fire department to check on structural integrity of homes as well as dozens of emergency calls flooding in from residents. Garnes said that about 60 emergency calls came through in the immediate aftermath of the quake.

Those who received early cellphone alerts ranged from residents already experiencing the shaking to some who didn’t feel the quake at all.

“Thank goodness for shake alert! I’d have fainted otherwise! 8+ second warning of severe shaking,” said one Twitter user.

Others complained they were notified despite being out of the quake’s range.

“Scared the heck outta my wife! Glad to know the notification works, but I wish there was a way to modify the location range a bit more. Now I’m trying to fall back asleep,” another Twitter user said.

Earthquakes

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— One of the most important things you can do to prepare for an earthquake is talk to your neighbors, writes seismologist Lucy Jones.

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— How does California’s earthquake early-warning system work? And what apps should you have on your phone?

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De Groot said the alert system must balance unnecessary notifications for those outside an earthquake’s range with making sure as many residents as possible who could be affected receive a notification.

The number of people notified exceeded the 2.1 million earthquake alerts sent in October when a magnitude 5.1 earthquake struck under the mountains of San Jose.

There are many apps that can deliver alerts in California triggered by the USGS ShakeAlert system: MyShake, QuakeAlertUSA and ShakeReadySD, an app developed for San Diego County but that works statewide.

While those closer to the epicenter reported feeling the shaking, Richard Allen, a seismologist and director of the UC Berkeley Seismological Laboratory, said the movement was weaker than expected at greater distances.

“For this earthquake, we’d expected people to feel it in the Bay Area, but very few people felt it in the Bay Area,” he said. “The intensity was lower than you’d expect for an earthquake like this.”

Allen said this quake was the biggest in magnitude since the MyShake app — which was built by UC Berkeley and funded by the California Governor’s Office of Emergency Services — was created.

“This is getting up there, but it’s not at the level where events do a lot of damage,” he said. “This is reminder of the impact of earthquakes and the impact that it’s gonna have on us.”

Times staff writer Alexandra E. Petri contributed to this report.