FRESNO, Calif. – If you received an alert before Tuesday night’s magnitude 5.2 earthquake that originated near the Kern County town of Lamont, you were probably one of millions, according to Gov. Gavin Newsom’s office.
These warnings come from ShakeAlert, a public safety notification system developed by the U.S. Geological Survey (USGS) and rolled out across California in 2019. Earthquakes travel so quickly across the Earth’s surface that warnings can arrive just seconds before the quake actually starts. But Robert de Groot, leader of the USGS’s ShakeAlert team, says every second counts.
“The recommended protective measure is to lie down, take cover and hold on. And that should only take a few seconds,” he said. The notifications can also be used by critical infrastructure such as public transport, hospitals and fire stations.
“Anything we can do to shorten the time between the detection of the earthquake on the surface and the time a message comes on someone’s phone – or the train slows down, the water valve is turned off or the fire station door is opened – is of benefit to us,” de Groot said.
Shakealert relies on data recorded by a network of hundreds of seismographs across the western states, as well as a handful of extremely powerful data centers.
“The principle is that we register an earthquake as soon as it reaches the Earth’s surface,” said de Groot. “We pass this information very quickly to a processing center, and … this processing center can estimate the magnitude of the earthquake in about a second, determine its location and determine how strong the quake may be around it.”
This information is shared with Google and other companies, who then send alerts to mobile phones near earthquakes, similar to how AMBER alerts and severe weather warnings are delivered.
Whether someone receives a notification at the right time depends on a number of external factors, including the strength of the network connection, but also the phone’s operating system.
If you’re using an Android smartphone, you should automatically be opted in to such public safety alerts. You can check if they’re allowed in your phone’s “Wireless Emergency Alerts” settings.
If you are using an iPhone, you may not necessarily be registered and can check the permissions in your phone’s “Local Awareness” settings.
To be doubly prepared, you can download a free app called MyShake, which delivers push notifications based on your home location and customizable notification settings.
