California Launches Earthquake Early Warning System

California launched an earthquake early warning system combining a smartphone app with wireless emergency alerts, Gov. Gavin Newsom (D) said Thursday. It uses ground motion sensors to detect earthquakes, then sends alerts through the app to provide “seconds of warning,” which is “enough time to drop, cover and hold on to help prevent injury,” the governor’s office said. The app will deliver alerts for earthquakes exceeding magnitude 4.5.