Los Angeles has unveiled its long-anticipated earthquake early warning app for Android and Apple smartphones, which is now available for download.

ShakeAlertLA, an app created under the oversight of Mayor Eric Garcetti and the city, is designed to work with the U.S. Geological Survey’s earthquake early warning system, which has been under development for years. It’s designed to give users seconds — perhaps even tens of seconds — before shaking from a distant earthquake arrives at a user’s location.

“ShakeAlertLA sends you information when a 5.0 or greater earthquake happens in Los Angeles County, often before you feel shaking,” the app says.

Garcetti is scheduled to make an official announcement unveiling the system Thursday morning. The app, which is also available in Spanish, was built under a contract with AT&T. It was published quietly online on New Year’s Eve, and by Wednesday morning, users of social media had already found it and begun tweeting their excitement about the release of the app.


For more than a year, the mayor has talked about providing an earthquake early warning app for Los Angeles residents, even as it seemed that making it a reality would be difficult.

But in October, Garcetti seemed optimistic that ShakeAlertLA would be unveiled by the end of 2018 if it passed initial testing among thousands of city employees.

“By advancing earthquake early warning technology, we are making Los Angeles stronger, making Angelenos safer,” the mayor told reporters in October. “And it’ll help save lives, most important, by giving people those precious seconds to stop elevators, to pull to the side of the road, to drop, cover and hold on.

“All that will not happen the first day we launch,” Garcetti said. “But together, with the private sector, we will build the software and the hardware that will allow us to be able to anticipate and react to an earthquake before we even feel it here.”


Warnings could soon be made more broadly available statewide. Josh Bashioum, founder of the Santa Monica company Early Warning Labs, which has been closely working with the USGS, said it hopes to release a beta version of its app, QuakeAlert, to as many as 100,000 test users across California soon.

So far, 90,000 people have signed up to be on the company’s wait list. That release will be kept on a test basis as experts determine whether there are any bottleneck delays in issuing push alerts.

× BART has tested the ShakeAlert system, designed to trigger trains to stop in the event of an earthquake, in Oakland.

A warning time of a few seconds can save lives, allowing utilities to turn off large high-pressure fuel lines, doctors to stop surgeries, transit agencies to slow trains and schoolchildren to shelter under desks.


Earthquake warnings work on a simple principle: Seismic shaking travels at the speed of sound through rock — which is slower than the speed of today’s communications systems. Earthquake sensors that detect a big earthquake that starts at the Salton Sea and has begun to travel up the San Andreas fault could sound an alarm in Los Angeles, 150 miles away, before strong shaking arrived in the city, giving Angelenos perhaps more than a minute to prepare.

The system is not likely to be perfect, especially in its first few years of service. As residents of Japan, Mexico and other places that already have the alerts have learned, the system comes with false alarms and missed warnings. And early warnings probably won’t be possible for users at the epicenter of a quake.

Yet the early warning systems have had tremendous support in other countries because the benefits when the systems work far outweigh the disappointments. The system helped prevent deadly derailments of high-speed trains in Japan before shaking arrived from the magnitude 9.1 earthquake of 2011, for instance, signaling the trains to slow down. Memorably, the national Japanese broadcaster NHK aired an earthquake warning about 90 seconds before the strongest shaking arrived in Tokyo.

Warnings that buzzed in classrooms gave some students enough time to shelter. According to accounts collected by Richard Allen, director of the Berkeley Seismological Laboratory, students in an elementary school classroom in the northeastern Japanese city of Sendai had 10 seconds to get under their desks before the shaking arrived.


One study found that several million people near the epicenter received an early warning 15 to 20 seconds before the strongest shaking hit. A poll found that 90% of those surveyed approved of the Japanese early warning system after that quake.

Residents of Mexico City have been generally positive about their earthquake early warnings, even when they received an alert that wasn’t followed by shaking, American scientists studying that system said. Residents would rather get false alarms than no warning before shaking hits, the researchers found.

“There seems to be general acceptance of the technical limitations of the early warning system in exchange for some measure of peace of mind,” the scientists wrote for the journal Earth & Space Science News.

Mexico and Japan built their systems after the 1985 Mexico City and 1995 Kobe temblors, respectively — severe earthquakes that each killed at least 5,000 people.


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Setting expectations can be important. In Japan, an awareness campaign led to 78% of the public understanding the possibility of false alarms.

A prototype system has proved successful in many recent minor and moderate California quakes, notably the 2014 magnitude-6 earthquake that hit Napa, giving San Francisco eight seconds of warning. Earlier that year, scientists in Pasadena got six seconds of warning when a magnitude-5.1 earthquake hit La Habra.

There are 865 earthquake sensing stations online for the early warning system on the West Coast, including 615 in California, but 810 more are needed, officials said. Too few sensors could mean, for instance, that Los Angeles would experience delays in warnings from an earthquake that starts in Monterey County and barrels south along the San Andreas fault.


The state budget that passed in 2018 authorized an additional $15 million to build out the remaining sensors that are needed for California to have a complete warning system. By this spring, California’s network is expected to be 70% complete, and by 2021, officials hope, all 1,115 seismic sensor stations intended for California will be online.

The system has become more popular with federal officials too. In March, as part of the $1.3-trillion budget bill approved by Congress and signed by President Trump, officials approved $22.9 million for the project, funding that more than doubled how much the warning system got in the previous year’s budget, $10.2 million.

Observers have credited a bipartisan coalition in the House of Representatives, including the backing of Rep. Ken Calvert (R-Corona), outgoing chairman of an influential House subcommittee, and the early support of Rep. Adam B. Schiff (D-Burbank) for winning wider congressional support for the system. The Trump administration had requested to end federal funding for the program.

The Trump administration has recently changed its rhetoric. In October, the Department of the Interior issued an order to expedite the approval process for the installation of seismic sensors on federal land, a process that has been bogged down by red tape.


The city spent $300,000 on the ShakeAlertLA app, which was created after AT&T won a contract that was put out for competitive bids. The bill was footed by the nonprofit Annenberg Foundation, which contributed $260,000, and $43,000 from a nonprofit established by Garcetti, called the Mayor’s Fund for Los Angeles, which accepts donations to fund local civic programs.

After its initial year, the city will need to begin paying the bills to maintain the app: $20,000 a year for web services and $27,000 annually for maintenance.

The programming is owned by the taxpayers and is open source, meaning that other cities and counties are free to take ShakeAlertLA’s code and use it for their own systems.

The app is currently set to sound an alarm only for magnitude 5 and higher earthquakes or those that cause at least light shaking, a level of ground movement that begins to affect public safety. There are still some bugs, including that the alarm won’t sound if users have their phones set to silent.


ron.lin@latimes.com

@ronlin