The only app that alerts you that an earthquake is happening in Los Angeles.
The description of ShakeAlertLA
ShakeAlertLA alerts you that an earthquake has been detected and that you may soon feel shaking. You can also use this app to prepare for an earthquake, get details on recent earthquakes, and find help after an earthquake. This app is brought to you by Mayor Eric Garcetti and the City of Los Angeles, and built on the ShakeAlert system developed by the U.S. Geological Survey.