Android phones around San Francisco’s Bay Area buzzed with a warning Tuesday morning: A 4.8 magnitude earthquake is imminent. “You may already be feeling shaky,” some of the messages were read. Over a million Android users have seen this warning. And for some, it comes seconds before the ground begins to move.
This is not the first time Android Marc Stogaitis, project lead for the Android Earthquake Alert System, says devices have received these alerts. But because the Bay Area was so densely populated, the alert hit enough tolls that the larger public took notice. Historically, earthquakes have occurred without warning, catching people off guard and with no advance notice to drop and hide. Alerts like these aim to eliminate some of the unpredictability of earthquakes — even if they are only for a few seconds.
“One of the things we’re trying to do is build an earthquake early warning industry,” said Robert de Groot, who is part of the team that operates ShakeAlert, a project under the US Geological Survey. . “We’re doing things we never really thought of.”
This technology doesn’t predict earthquakes — no one can, and neither does the USGS speak it doesn’t think it will learn to predict earthquakes “in the near future.” But it detects them earlier than people usually feel them. And experts hope that one day, warnings can be sent out even faster, giving people more time to get out of harm’s way.
Time to roll
Tuesday’s Android alert powered by data from ShakeAlert, which detects when an earthquake has started on the West Coast and provides information to state government agencies and third parties. And Google has taken steps to make that information more readily available during those precious seconds. First, the company rolled out alerts into its own system, sending push notifications to people with Android phones who are in an earthquake area without them having to download a separate app.
Here’s how it works: When an earthquake occurs, it sends lighter seismic waves, called P waves, through the ground. Not everyone in the earthquake area will feel these, but a network of 1,300 USGS sensors will. When four sensors are activated simultaneously, they send an alert to the data processing center. If that data meets the matching criteria, the ShakeAlert system determines that a stronger S-wave, the kind that can cause damage and injure people, may be on its way. Then, alert systems, like Google’s, an app called MyShake, or government agencies like the Federal Emergency Management Agency and transit systems, interpret the data and send alerts. .
There are limitations. Those S waves move at a uniform speed; The closer a person is to an earthquake, the less likely they are to receive a warning before feeling a tremor. USGS sensors are expensive and strategically located on the West Coast. (There will be a total of 1,675 by 2025, de Groot says.) Also, the rapidly aggregated intensity measurements are preliminary; Tuesday’s Android Alert warned of an approaching 4.8 magnitude earthquake, but the measurement results came later. adjusted to 5.1.
