New quake app has shaking countdown

A new earthquake early-warning app for smartphones has been released, offering users across California the ability to see a countdown before shaking arrives.

Available for iOS and Android phones, QuakeAlertUSA also offers the ability for phone owners to individually tailor when the app is triggered – for weak, light or moderate shaking.

The app by Santa Monicabased Early Warning Labs uses the same data source as the other two apps that have been available – the US Geological Survey’s ShakeAlert system, powered by hundreds of earthquake sensors across California. Two other apps are available for earthquake early warning but don’t offer countdowns or the ability to ignore warnings for weak and light shaking; they are the University of California, Berkeley’s MyShake app, which offers statewide coverage, and the city of Los Angeles’ ShakeAlertLA app for users physically in Los Angeles County.

California authorities have also begun to issue alerts via text message, through the Amber Alert-style Wireless Emergency System. Those alerts do not require downloading an app or having a smartphone to receive the apps, but that system may be slower than the apps and is set to go off for only more relatively stronger shaking than the smartphone apps.

The mildest shaking that can trigger an alert for QuakeAlertUSA’s app is weak shaking, or Level 3 on the Modified Mercalli Intensity Scale, defined as felt quite noticeably by people indoors, especially on upper floors of a building, and can cause standing motor rocks to slightly rock. Some might think the shaking is resulting from the vibrations felt when a heavy truck passes.

This threshold is the same used by ShakeAlertLA and MyShake.

Users of the QuakeAlertUSA can also set the alarm to ring only for more substantial shaking, such as one that’s light, or Level 4 for the intensity scale.