California’s new statewide earthquake early warning system, the MyShake app, sent out its first public alert on Tuesday, a milestone for the app. The warning was for a magnitude 4.3 earthquake that occurred in the mountains between the Central Coast and San Joaquin Valley and that was originally estimated at 4.8.
According to experts quoted by the LA Times, the alert was sent out to 40 people and took 8.7 seconds to go out. The app, released publicly last October, uses earthquake data provided by the U.S. Geological Survey’s backbone ShakeAlert system to send out early warning alerts.
Such apps work because today’s communications systems have the capacity to send alerts faster than seismic waves can move. This is especially useful in earthquakes with strong magnitudes, giving people seconds to prepare for the shakes to come.
Luckily, the weak magnitude of this quake ensured it was only felt close to the epicenter in the Cholame Valley and that no damage was reported. The LA Times even reported the quake was so mild that no one even called the fire department.
“I didn’t see any damage or effects from the earthquake,” said Chief Jonathan Stornetta.
In addition to the MyShake App, the city of Los Angeles has the ShakeAlertLA app developed by AT&T. Both apps will be triggered if an earthquake of magnitude 4.5 or greater is recorded or a Modified Mercalli Intensity (MMI) of 3.
The MyShake App went into effect nearly two months ago on the 30th anniversary of the Loma Prieta quake of 1989. At the time, UC Berkeley, the app's developer, reported tests that showed alerts could reach users in about 3.7 seconds.