California earthquake warning app is now available on more devices. Here's how to get it

Rong-Gong Lin II, Los Angeles Times on Dec 19, 2024

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LOS ANGELES — California’s free earthquake early warning app is now available for Mac computers and Chromebooks — a major expansion of access for the warning system, which has been available for years on cellphones.

The MyShake app, developed by the University of California, Berkeley, is one of the most popular ways to receive earthquake early warnings generated by the U.S. Geological Survey’s ShakeAlert system, which provides alerts in California, Oregon and Washington. The app has been downloaded nearly 4 million times since it launched in late 2019.

MyShake was already available on iPhones, iPads and Android phones. UC Berkeley is also working to make MyShake available for the Windows operating system, said Richard Allen, director of the Berkeley Seismology Laboratory.

More than half a million people in California got early warnings through MyShake on Dec. 5 for a magnitude 7 earthquake that struck in the Pacific Ocean 30 miles off the Humboldt County coast and Dec. 9 for a magnitude 5.7 earthquake centered about 50 miles southeast of Reno, which was widely felt across Central California.

Some users got up to 15 seconds of warning before they felt shaking from the earthquake off Humboldt County, officials said. And some people got more than 10 seconds of warning about the Nevada earthquake.

On Aug. 6, more than 517,000 early warning alerts went out to MyShake users for a magnitude 5.2 quake that struck Kern County, near the Grapevine section of Interstate 5. People throughout Southern California said they got a few seconds of warning before they felt shaking.

Earthquake early warning systems operate on the scientific principle that shaking waves moving through rock travel slower than today’s telecommunications systems — similar to how you might see a bolt of lightning seconds before hearing thunder.

For example, it would take more than a minute for a magnitude 7.8 earthquake that starts at the Salton Sea along San Andreas fault to be felt 150 miles away in Los Angeles.

The farther you are from the epicenter, the likelier it is that you could get more warning. But if you’re very close to the epicenter, the warning might arrive after you’ve already started to feel shaking.

The USGS ShakeAlert system relies on a vast array of seismic sensors in the ground to detect shaking as soon as it happens. That information is then sent to computers to determine whether and where to send an alert.

Officials advise people to drop, cover and hold on when they hear an alert of incoming shaking.

Gov. Gavin Newsom hailed the expansion of the MyShake app, which is provided in partnership with the California Governor’s Office of Emergency Services, to more devices.

“I encourage Californians to download the MyShake app on their phones, laptops or tablets to receive these important alerts, and make sure emergency notifications on mobile devices are turned on,” Newsom said in a statement.

The MyShake app is set to trigger alerts if a quake is estimated at magnitude 4.5 or higher and the intensity of shaking at the phone’s location is expected to be at least “weak”— defined as Level 3 on the Modified Mercalli Intensity Scale. That intensity of shaking is defined as one that’s noticeable to people indoors, especially on the upper floors of a building, and may cause cars to rock slightly. Some people indoors might liken the feeling to vibrations from a passing truck.

There is a setting you can change on your iPhone to improve the speed, accuracy and reliability of emergency alerts, Apple says. To do that, you can turn on “local awareness” by going to settings, then notifications; scrolling down to “Government Alerts,” then tapping “Emergency Alerts” and navigating to the option.

On its website, MyShake suggests opening the app every month or so to keep it “fresh and ready to receive alerts. Not using the app for a prolonged period might cause the app to be put into deep sleep.”

One easy way to do this, MyShake suggests, is to click on the app when it notifies you — without any urgent, alarming warning sounds — of a significant earthquake somewhere around the world, which typically happens every two weeks. “By tapping on this notification, and opening the MyShake app, you can keep the app fresh, and not have to rely on your own reminders.”

MyShake is also now available in six languages: English, Spanish, Tagalog, Korean, Vietnamese and Chinese — the last voiced in Mandarin, and using traditional characters. MyShake will use the first language that it supports from your device’s language and region settings, but on an iPhone you can change the language by going to settings, then apps, and selecting MyShake before choosing a preferred language.

People who don’t have computers or smartphones can still get quake alerts on their cellphones — but only for those in which a higher magnitude or higher level of shaking is projected at their location. Those alerts are sent through the Wireless Emergency Alerts system, similar to Amber Alerts.

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