Temblor jostles Bay Area
An estimated 9.8 million people felt a magnitude 4.4 earthquake that rumbled across the Bay Area early Thursday, the U.S. Geological Survey reported.
It was felt throughout the region, with people more than 150 miles away reporting to the agency that they felt the shaking for perhaps five to 10 seconds, according to officials. Near San Francisco International Airport, several jolts could be felt.
According to responses on the U.S. Geological Survey website, more than 9.8 million people were in the zone that could feel weak, light or moderate shaking. The earthquake was downgraded to a magnitude 4.4 after initial data suggested it was larger.
Items in a San Leandro store were knocked off the shelves, video from KRON4 showed, and Bay Area Rapid Transit started Thursday with train delays as workers performed a systemwide check for damage about 4 a.m.
The checks were completed about 5:30 a.m. with no reports of damage, the agency tweeted.
The earthquake was centered along the Oakland-Berkeley border, just north of the Claremont Hotel. The epicenter of the earthquake is in the area of the Hayward fault, one of the most feared in the Bay Area, which could produce a magnitude 7 or greater earthquake and is directly underneath heavily populated areas.
San Francisco’s emergency managers said all city facilities and infrastructure would be inspected Thursday, though there were no initial reports of damage or injuries.
A magnitude 4.5 earthquake is not expected to cause major damage, said USGS seismologist Robert Sanders. Still, “there’s always a possibility of some minor damage to older structures in the area.”
The shaking was strong enough to wake people up when the earthquake hit at 2:37 a.m. One person in San Francisco said it was strong enough to knock picture frames from the wall.
As is always the case, there was a 5 percent chance the temblor could trigger a larger quake in the near future.
“We live in earthquake country so we should all expect earthquakes,” said Keith Knudsen, deputy director of the USGS Earthquake Science Center. “There will likely be aftershocks. There’s a small probability there will be bigger ones.”
An earthquake early warning system under development worked—and sent data about the temblor to computers 4 seconds after it began, Knudsen said.
In a real-world scenario, the jolt felt Thursday would likely not be considered big enough to issue a warning to residents in the path of the shaking, he said.
“But having one up and running and testing it is really valuable to us. How much warning time one gets depends on how far away they are, how big it is, how dense the seismic network is and how rapidly the computers are processing,” he said.
The system would typically allow a few seconds of warning for people not close to the epicenter—which would be enough time in theory to slow trains, stop elevators and allow people to brace themselves.