ShakeAlert earthquake warnings can give people time to protect themselves – but so far, few have actually done so
My Facebook feed exploded shortly after noon on Dec. 20, 2021, with news from friends and family in northern California: A “big one!” The 6.2 magnitude earthquake they’d just experienced had its epicenter on the coast near Petrolia.
Yet many social media posts weren’t focused on the earthquake itself, but rather the alert sent to cellphones seconds before – or, for some, just as – major shaking began.
The ShakeAlert system is a remarkable technology, years in the making. It has the potential to save tens of thousands of lives in areas where high-magnitude earthquakes occur by providing a few seconds’ warning – enough time for people to take basic safety precautions. Marvelous as it is, though, ShakeAlert saves lives only if people understand what to do when they receive such an alert – and do it.
For people near the epicenter, the time it takes to process the data and send an alert may mean it arrives just as, or possibly even seconds after, major shaking begins. Even this roughly simultaneous notice is valuable, as it helps people realize what is happening, which often isn’t obvious.
For those further away from a quake’s epicenter, an alert may arrive seconds, or even tens of seconds, before strong shaking. That’s enough time to automatically shut down or alter the operations of key systems – for example, to slow or stop trains, control equipment involved in delicate medical procedures, or electrical grids. It’s also enough time to prepare mentally, as well as to take potentially life-saving protective action.