Android Earthquake Alerts: A global system for early warning (opens in new tab)

Google’s Android Earthquake Alerts system utilizes the onboard accelerometers of billions of smartphones to create a global, crowdsourced seismic network. By detecting the initial P-waves of an earthquake and rapidly processing aggregate data, the system provides critical early warnings to regions that often lack traditional, expensive seismic infrastructure. This technological shift has expanded earthquake early warning access from roughly 250 million people to over 2.5 billion worldwide.

Leveraging On-Device Accelerometers

• Mobile accelerometers, typically used for screen orientation, function as mini-seismometers capable of detecting the initial, fast-moving P-waves of an earthquake.
• When a stationary phone detects these vibrations, it sends a signal along with a coarse location to a centralized detection server.
• The system aggregates these signals to confirm the event and estimate its magnitude before the slower, more destructive S-waves reach the population.

Global Reach and Implementation

• Active in nearly 100 countries, the system has detected over 18,000 earthquakes ranging from M1.9 to M7.8.
• The system has issued alerts for over 2,000 significant earthquakes, resulting in approximately 790 million alerts sent to users globally.
• By utilizing existing consumer hardware, the system serves as a "global safety net" for earthquake-prone regions that cannot afford traditional ground-based sensor networks.

Magnitude Estimation and Accuracy

• A primary technical challenge is the trade-off between speed and accuracy; the first few seconds of data are limited but essential for providing early warnings.
• Over three years, the system's median absolute error for initial magnitude estimates has been reduced from 0.50 to 0.25.
• The accuracy of these smartphone-based detections is now comparable to—and in some cases exceeds—the performance of established traditional seismic networks.

User Alerts and Real-World Impact

• The system delivers two tiers of notifications: "BeAware" alerts for light shaking and "TakeAction" alerts, which use full-screen takeovers and loud sounds for intense shaking.
• During a magnitude 6.7 earthquake in the Philippines, the system issued alerts 18.3 seconds after the quake began, providing users further from the epicenter up to 60 seconds of lead time.
• To maintain privacy, the system relies on coarse location data and requires users to have Wi-Fi or cellular connectivity and location settings enabled.

For users in seismic zones, ensuring that Android Earthquake Alerts and location services are enabled provides a vital layer of protection. This crowdsourced model demonstrates how ubiquitous consumer technology can be repurposed to provide essential public safety infrastructure on a planetary scale.