Android smartphones around the world have actively helped provide earthquake alerts using their acceleration sensors. Between 2021 and 2024, these phones sent thousands of successful warnings to people living in regions subject to the earthquake in 98 countries.
Since 2020, Google has included its Android Earthquake Alert (AEA) system in its phones to detect seismic waves and preceded an earthquake and provide alerts. The company and the seismology laboratory of the University of California Berkeley have published data in a new article in Sciencedetailing the performance and methods of algorithm in the past three years.
The AEA system was deployed for the first time in the United States in 2020, followed by New Zealand and Greece in 2021, then the rest of the world.
He issued alerts for 11,231 events, notably in front of Turkey-Syria (magnitude 7.8), the Philippines (6.7) and Nepal (5.7), all in 2023 and the 6.2 event of Turkey in Turkey in April 2025. In the Philippines, the Syria of Turkey and the Nepal Conderies, the users received 10 to 60 seconds of derogation from the Philippines, Türkiye.
The system has so far detected more than 18,000 variable amplitudes earth tremors, including more than 2,000 strong earthquakes (moderate or more tremors on the MMI scale) and has issued a total of 79 alerts is growing. The AEA team also questioned users between February 2023 and April 2024. Some 79% of 1.5 Lakh users said they had found the alerts very useful.
Crowdsources AEA report the accelerometer of a phone, a sensor that measures acceleration. On stationary phones, accelerometers can detect faster P waves from an earthquake, which extend and press the geological material they cross.
When an accelerometer detects these waves, it sends a signal to the Google earthquake detection server, which then analyzes the data from other phones nearby to confirm that the wave is real.
This data is collected and processed quickly with the location and extent of the waves. The objective is to issue an alert before the arrival of slower and more destructive S waves. While P waves can move through solids and liquids, S waves move only through the solids. They also move from top to bottom, moving the material they cross.
The AEA does not monitor surface waves, the third type of wave to reach an earthquake. Surface waves are much slower and only cross the external layer of the crust, and are generally responsible for the most above damage.
Algorithm at work
To detect an earthquake, all bench smartphones on their accelerometers to feel vibrations on surfaces and in the air. Earthquakes produce many vibrations of this type before the energy that causes damage really reaches a location. The extent of the damage caused by an earthquake increases with each type of wave which reaches a location on the surface.
The algorithm estimates the distance to the epicenter in two ways. If it is less than 200 km from the surface, it is equal to the difference in time between the arrival of S and P waves multiplied by 8 km / s. For deeper epicentres, the algorithm includes additional methods to take into account the movement of waves via the coat.
The algorithm emits two types of alerts: “Beaware” alerts for imminent light tremors and “Takection” alerts for stronger tremors; The latter are accompanied by an audio warning which replaces the parameters “does not disturb”. Alerts can also be activated manually and deactivated.
According to the newspaper, the system has increased the number of people with access to the early alert of the earthquake by almost a factor of 10: approximately 25 people in 2019 to 250 crore of people in 98 countries.
The authors of the article, who are also affiliated with Harvard University and Google Germany, also underlined the gaps in the AEA – including its inability to estimate the magnitude and the tendency to relay warnings after the tremor.
They also documented these problems in detail and specified adjustments to solve many problems, including the reduction of the absolute median error in the first estimates of the magnitude of an earthquake of 0.5 to 0.25. They also drawn three false positives in the 11,321 events with two hurricanes and a mass telephone vibration from an unrelated alert, and included fixes for alerts to be issued more quickly.
“”The proliferation of low -cost sensors in consumer products provides opportunities for new observations from our physical and global physical environment. The AEA makes it possible to make global observations of earthquakes, ”wrote the authors.
Sandhya Ramesh is an independent scientific journalist.
Published – July 27, 2025 05:40 AM Ist
