Google hooked billions of mobile phones to detect earthquakes around the world and send alerts

The study shows how the technology giant uses motion sensors on phones to spread earthquake warnings in more countries.

Technology giant Google used motion sensors on more than two billion mobile phones between 2021 and 2024 to detect earthquakes, and then sent automatic alerts to millions of people in 98 countries. In an analysis of data published in Science today1, Google scientists say that the technology recorded more than 11,000 earthquakes and worked on a par with standard seismometers. Earthquake researchers who did not participate in the experiment are impressed by the performance of the system, but argue that government officials will need access to additional information about the patented technology before relying on it.

Over the past few decades, earthquake warning systems using standard seismometers have been deployed in places such as Mexico, Japan and the west coast of the United States. But in 2020, Google announced that it would build a Crowdsourcing system to detect shocks at the earliest stages by tracking the collective shaking of Android phones. The results of the first three years of work, published today, show that the technology works and has improved over time. On average, thousands of people die from earthquakes every year, and with the help of the mobile alert system, the number of people who now have access to earthquake warnings has increased tenfold since 2019, Google reports.

"It's very impressive: most countries don't have an earthquake early warning system, and it can help provide this service," says Allen Hasker, a seismologist at the California Institute of Technology in Pasadena. But, says Hasker, he would feel better if Google provided independent scientists with more access to data and algorithms.

Scientists from Google say that they are as transparent as they can about how the system works and works. Due to privacy issues, sharing raw data from users' phones is a difficult task, they told Nature, but the scientific document is designed to shed as much light as possible on how the system works.

"This is really the origin of this article," says Richard Allen, a seismologist from the University of California at Berkeley and a guest lecturer at Google. "I hope that the community will recognize this and appreciate it."

Crowdsourcing detection

Android's earthquake alert system is based on quantity, not quality: research-level seismometers provide better data, but Google relies on the widespread use of modern Android smartphones, which collect and report motion data by default if users do not refuse to bypass the lack of sensitivity in any given device. In addition to mapping data from individual users to determine the origin and strength of earthquakes, the Google team has developed algorithms for analyzing the collected signals that contain regional differences in geology and building construction, and take into account how different phone models register movement.

The Google team says that there are still problems when it comes to detecting and issuing timely warnings about the largest and most dangerous earthquakes. For example, the system underestimated a couple of powerful earthquakes in Turkey in February 2023, as a result of which about 4.5 million earthquake warnings were sent to users. However, when Google scientists updated their algorithms and overestimated these earthquakes, the system predicted stronger earthquakes and sent more urgent "TakeAction" alerts that would have been received by ten million Android phones.

"This shows that they have been working on improving the system since 2023, with tangible positive results," says Harold Tobin, a seismologist at the University of Washington in Seattle.

But Tobin is also worried about the system's own nature. "For a public security system like this, the Android team is responsible for being very transparent about how it works so that civil authorities can make these decisions themselves."

Google has published a statement for Nature describing the alert system as an "additional" service that "is not intended to replace official earthquake detection or notification systems".