The city announced Wednesday that ShakeAlertLA is available for download on Android and Apple phones.
Based on a warning system developed by the U.S. Geological Survey, the app will alert when there's a quake of magnitude 5.0 or greater in the state.
Depending on where the quake hits, the app says the warning could arrive before, during or after the quake. It urges people who see the alert or feel the shaking to take precautions to avoid injury.