This is of practical interest to me because I live near the Cascadia Subduction Zone (CSZ) which is predicted to have a Magnitude 9 earthquake sometime in the (near??) future.
How Phones Alerted Millions Before Quakes Shook Venezuela
By Amy Graff and Martín González Gómez, The New York Times, June 27, 2026
…
Venezuela does not have a national early warning system of its own, but people with Android phones received alerts from Google’s Earthquake Alerts system, which can pull data from more than two billion phones equipped with built-in accelerometers. The same sensor that detects rotation on the screen can also sense vibrations from seismic waves.Venezuela does not have a national early warning system of its own, but people with Android phones received alerts from Google’s Earthquake Alerts system, which can pull data from more than two billion phones equipped with built-in accelerometers. The same sensor that detects rotation on the screen can also sense vibrations from seismic waves.
Google said the system, which is available in nearly 100 countries, sent warnings that reached 11.4 million people on Wednesday, giving users seconds or up to two minutes notice before back-to-back powerful earthquakes struck.
When P-waves start radiating from the epicenter, Android phones sense the vibrations, start collecting data and send it back to Google servers for processing. The servers use information from many phones to figure out if an earthquake is happening. The phones have to be stationary — on a tabletop or in a bag on the floor, for example, and not in the pocket of someone walking around — in order to sense an earthquake.
The system quickly estimates the earthquake’s location and magnitude and then pushes alerts to phones. All Android phones in the affected region receive the alerts.
Google sends out alerts for earthquakes of magnitude 4.5 and above, which are considered powerful enough to cause some damage. People receive different types of alerts depending on the estimated magnitude where they are. One blares a loud sound and uses urgent messaging to tell people to take immediate action in areas with potentially extreme shaking, another beeps to tell people to be ready, and a third cautions people to be aware in areas where lighter shaking could occur…
An estimated 70 percent of all smartphones globally run on Google’s operating system, Android. The earthquake detection system works wherever people are using the phones, even in countries without other alert systems, according to a paper published in 2025. Google started sending out alerts for earthquakes detected by Android phones in 2021, initially in New Zealand, Greece, Turkey, the Philippines and central Asia. It had expanded to 98 countries by 2023…[end quote]
Wow! This is really cool! But the CSZ system is different because it’s under continuous close sensing by the USGS. The same is doubtless true of the San Andreas Fault.
Google turns the phone crowdsourcing feature OFF in Washington, Oregon, and California.
Instead, Google partners directly with the USGS. In your region, Google uses the official government ShakeAlert data feed to push its built-in Android alerts.
The warning will come two ways.
- The Government (WEA/IPAWS): Once the USGS triggers the alert, FEMA broadcasts a Wireless Emergency Alert (WEA)—the same system used for AMBER alerts. This doesn’t rely on your cellular data plan, an internet connection, or app traffic. It uses a dedicated, prioritized radio frequency broadcast directly from the local cell towers straight to your phone’s hardware.
- Google (Android Earthquake Alerts): Google takes the same USGS data and pushes an operating-system-level notification to your phone. While incredibly fast, it must travel through the standard internet data pipeline (cellular data or Wi-Fi). If cell towers are instantly overloaded by millions of devices or if your data connection is weak, internet packets can bottleneck.
Several METARs live in earthquake zones so it’s good to know that our Android phones will warn us via the Google worldwide system even if we don’t have a government warning set up. I don’t know how iPhones can tap into this.
Wendy