Global earthquake detection and warning using Android phones.

Earthquake early-warning systems are increasingly being deployed as a strategy to reduce losses in earthquakes, but the regional seismic networks they require do not exist in many earthquake-prone countries. We use the global Android smartphone network to develop an earthquake detection capability, an alert delivery system, and a user feedback framework. Over 3 years of operation, the system detected an average of 312 earthquakes per month with magnitudes from M 1.9 to M 7.8 in Türkiye. Alerts were delivered in 98 countries for earthquakes with M ≥4.5, corresponding to ~60 events and 18 million alerts per month. User feedback shows that 85% of people receiving an alert felt shaking, and 36, 28, and 23% received the alert before, during, and after shaking, respectively. We show how smartphone-based earthquake detection algorithms can be implemented at scale and improved through postevent analysis. Editor's summary: Earthquake early warning systems depend on real-time analysis of waves detected at nearby seismic stations or by smartphone accelerometers. The latter approach, although less sensitive, is a promising way to offer alerts in areas without seismic stations. In a major step forward, Allen et al. describe the outcomes of an alert system rolled out to Android phones in 98 countries, which increased total warning system access 10-fold to 2.5 billion people over 3 years. Issuing more than 1200 alerts over that period, the system recorded low-magnitude errors and provided preshake warnings consistent with other detection systems but on a much larger scale. —Angela Hessler [ABSTRACT FROM AUTHOR]