USGS explains why ShakeAlert warned Bay Area residents of Truckee earthquake


SAN FRANCISCO, Calif. (KRON) – There was an earthquake over 180-miles away from the Bay Area Thursday night. However, some folks here in the Bay received a warning alarm from the USGS ShakeAlert System. 

A USGS scientist explains why that is a good thing.

Thursday’s 4.7 earthquake, centered near the town of Truckee, triggered the USGS Earthquake Early Warning ShakeAlert system. 

Daly City resident Antonio Maffei says he was surprised to receive an alert about a quake so far away from the Bay Area.

“So yeah, I was sitting at the kitchen table eating dinner and all of the sudden my watch started going off and made a very funny and alarming sound,” Antonio Maffei said. 

“I think last night was a success. It shows that the system is up and running,” Robert De Groot, with the United States Geological Survey, said. 

Robert De Groot is one of the early warning system coordinators at the United States Geological Survey in Pasadena. 

He explains why it is not unusual for people to receive messages from the ShakeAlert system from great distances.

“The shake alert system has to move very very quickly and it was relying on a seismic station in a very rural and rugged area to get its information. So initially the system thought it was a magnitude 6 earthquake. What happened instead it was a magnitude 4.7. If you have a bigger earthquake more people will end up getting alerted,” De Groot said. 

This Daly City resident explains why that explanation works for him.

“It was something definitely was alarming but I am glad it worked,” Maffei said.

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