California earthquakes: Advanced early warning systems warn millions

Most Californians know this depressing feeling.

The ground shakes, bringing your attention back. For a split second, Your mind considers the possibilities: A truck passing by? Someone dropping a heavy object on the ground?

But the truth quickly becomes obvious: EARTHQUAKE!

For centuries, people living in earthquake-prone countries have experienced seismic movements in this way. But in the past few years, technological innovation has created another option: a smartphone alarm that gives you a few precious seconds to prepare for the quake.

California begins offering free early earthquake warnings applications about five years ago. In 2024, after various improvements, a series of moderate earthquakes and wider use, the network finally begins operating.

More than 5.4 million early warning alerts were sent on Tuesday 5.2 magnitude earthquake which struck Kern County about 18 miles southwest of Bakersfield and 14 miles northwest of the unincorporated town of Grapevine.

“Your heart rate definitely increases and your adrenaline starts pumping no matter what,” Jennifer Lazo, chief of innovation and technology at the Los Angeles Department of Emergency Management, said of receiving alerts. “But I think it’s key to understand what the noise means, to understand how to quickly look at the message and then quickly take action.”

Lazo got the alert on her phone Tuesday night when she began standing in the lobby of the Hollywood Pantages Theater during a break in a show with her mother. She told her mother to stay put until they could be sure the quake wasn’t serious.

She and her mother didn’t feel much, but when they returned to their seats, they realized that many people in the audience had felt stronger shaking.

This is the third time in the past year that multiple Southern California residents have reported receiving ShakeAlert warnings. Many marvel at the technology’s ability to warn them before they feel the shaking, as it did with the July 29 Mojave Desert earthquake that big enough to feel a little scared but without causing significant damage.

“It’s nice that we have a series of these … ‘big enough’ earthquakes so that we can train the system” and give “people a chance to get used to earthquake early warning,” said Robert de Groot, operations manager for the U.S. Geological Survey’s ShakeAlert system, which generates alerts distributed to various apps. “That’s really important.”

Scientists want people to get used to the warnings, which they hope will become a part of life in California and other earthquake-prone areas of the West Coast.

On Tuesday, residents in cities including Anaheim, Long Beach, Pasadena, Redondo Beach, the San Fernando Valley, the San Gabriel Valley, Ventura and West Los Angeles reported receiving warnings seconds before they felt the tremors.

Some even reported a 30- to 45-second warning before the quake. They may have felt the first aftershock — a magnitude 4.5 that struck less than a minute after the magnitude 5.2 quake.

In West L.A., De Groot said his wife first saw the alert on her phone and said, “What’s this Kern County thing?” He said the initial warning estimated that their home would experience some mild shaking, and after about 15 seconds, they felt it — shaking he described as “a very slight back and forth shake” lasting about four seconds.

Tuesday’s 5.2 magnitude earthquake was the worst attack on Southern California in three years. Other recent earthquakes in which many people reported feeling tremors include the July earthquakes size 4.9 earthquake with its epicenter in the Mojave Desert and last year’s 5.1 magnitude earthquake near Ojai in Ventura County, which, as we know, struck on the same day, big storm due to a weakened Hurricane Hilary that was looming over the area.

Within seconds of Tuesday’s quake, the early warning system rated it a magnitude 6.0, then lowered it to 5.7 a short time later. The USGS website initially reported the quake as a magnitude 5.3, but later lowered it to 5.2.

Of course, there were people who received warnings but did not feel the tremor, while others who were close to the epicenter — as far as 20 miles from the source of the earthquake — felt the tremor before they received the warning.

But that’s to be expected: a compromise aimed at getting warnings to as many people as possible before they feel the earthquake.

The system works on a simple principle: Earthquake tremors travel at the speed of sound through rock—slower than today’s communication systems. For example, it takes more than a minute for a 7.8-magnitude earthquake that begins in the Salton Sea, along the state’s longest fault, the San Andreas, to be felt 150 miles away in Los Angeles.

Many people, however, are not receiving alerts because their phones do not have an earthquake early warning app installed. While Google’s Android operating system has a built-in app, Apple’s iOS system on iPhones does not.

More than 517,000 alerts sent MyShake users, According to the governor’s office, De Groot added that Google has sent more than 4.9 million alerts to Android users.

How to Get Early Earthquake Alerts

iPhone owners can receive early earthquake warnings by downloading a free app MyShake app, developed by UC Berkeley and provided in partnership with the California Governor’s Office of Emergency Services, that notifies users in California, Oregon and Washington. San Diego County also offers a free SD Emergency application that includes the ShakeReadySD earthquake early warning tool.

People who don’t have smartphones or don’t have an early warning app installed can still receive earthquake alerts on their mobile phones—but only if a higher intensity or higher level of shaking is predicted for their location. Those alerts are sent through the Wireless Emergency Alert system, similar to Amber Alerts.

Android phones and those with the MyShake or ShakeReadySD apps installed have the lowest threshold for early earthquake warnings: they are set to trigger alerts if an earthquake is estimated to have a magnitude of 4.5 or higher and the intensity of the shaking where the phone is located is expected to be “weak” — defined as level 3 on the modified Mercalli intensity scale.

People without Android phones or apps can still get early warnings automatically through the Wireless Emergency Alert system. Its thresholds are a bit more conservative, though: Alerts are sent to cellphones only if the earthquake is expected to have a magnitude of 5 or more and is expected to be “light,” defined as a level 4 on the Mercalli scale.

An unknown number of phone calls received wireless emergency alerts Tuesday evening.

People may remember downloading earthquake early warning apps released by the city of Los Angeles on New Year’s Eve 2018 — ShakeAlertLA — but that app was retired in late 2020.

Researchers are urging California residents to download an early warning app and say it’s a good idea to have more than one way to receive notifications on your phone. MyShake is available for both Apple iOS and Android systems.

“It’s worth organizing all this. It’s worth getting this technology and using it,” De Groot said. “It works… it gives us a chance to get used to living” with early warnings of earthquakes.

Other nations — including Japan, Mexico, Taiwan and Turkey — have working early warning systems. They are a part of life in Japan: Schoolchildren are taught to roll, cover and hold on when they hear alerts; television shows are interrupted by the familiar sound of a voice-over detailing the expected quake; and cellphones automatically broadcast audible alerts.

On Thursday morning, 7.1 magnitude earthquake A tsunami was reported off the eastern coast of Japan’s southern main island of Kyushu, briefly sparking fears of a possible tsunami while authorities assessed the region for potential damage.

According to local media, no major damage was reported, and no tsunami was expected in California. The epicenter of the earthquake was about 550 miles southwest of Tokyo and about 14 miles southeast of Miyazaki.

Taiwan’s effective early warning system attracted a lot of attention in March, with many people delighted with it TV journalists who warned viewers of the strongest 7.4-magnitude quake before it reached their studio, and continued broadcasting warnings even as they struggled to stand and ceiling lights crashed into each other.

Initial talks begin on launching earthquake early warning system in California over a decade ago. Officials say it’s now clear that years of investment, made possible in part by support from elected officials in Washington and Sacramento, are finally bearing fruit.

“Our investments in cutting-edge, innovative technologies are paying off. Efforts like these have saved us precious seconds between the time alerts reach Californians’ cellphones and the time the ground begins to shake,” said Gov. Gavin Newsom, who announced MyShake App Release in 2019, he said in statement on Wednesday.

“Californians, I encourage you to download the app,” he added. “It could save lives!”

Getting the first warning can be a bit unsettling, but this system can help prepare Californians in the event of larger earthquakes.

Lazo, of the Los Angeles Department of Emergency Management, said it was exciting to see the alerts in action, not just as theoretical exercises.

“It shows a lot of hard science working that will actually have an impact on public opinion and hopefully make people safer,” she said. “And that’s a great thing to see. It’s a whole new frontier for us in earthquake response.”

Times journalists Luke Money, Joseph Serna and Ruben Vives contributed to this article.