Editor’s summaryEarthquake 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 th...