Earthquake near SFO jolts Bay Area residents on Friday

An earthquake centered on the upper Peninsula, near San Francisco International Airport, rattled Bay Area residents Friday night.

The quake initially registered as a magnitude 3.9, but it was downgraded to 3.7, according to Robert de Groot, team lead for the

U.S. Geological Survey's ShakeAlert.

“This sort of earthquake is your garden variety, runof-the-mill earthquake,” said de Groot, adding that “magnitude 3 and magnitude 4 (earthquakes) are very common” in California.

The quake struck at 6:38 p.m. about 1.2 miles north of Millbrae and at a depth of just more than 8.1 miles, according to the USGS website. The agency's map placed the epicenter under SFO's runways.

It was felt in San Francisco and Oakland, with reports coming from as far away as Monterey and Santa Rosa. More than 10,000 people logged their observations at the USGS Did You Feel It website.

There were no immediate reports of damage, according to the North County Fire

Authority.

The earthquake also had “no impact to SFO operations,” according to airport spokesman Doug Yakel.

BART service was stopped for about 20 minutes following the quake, but was running again by 7 p.m., KRON Channel 4 reported.

Also Friday night, at 8:21 p.m., a magnitude 2.9 earthquake was recorded in the foothills east of San Jose.

Friday's earthquake follows last week's sizable seismic event in Northern California, a magnitude 4.2 quake that struck the Sacramento County town of Isleton on Oct. 18 and caused shaking throughout the Delta area and well beyond.

Many Bay Area residents already are on high alert this time of year during the anniversary of the

Loma Prieta earthquake that rocked the region on Oct. 17, 1989. So, two backto-back quakes might cause some concerns.

Yet, de Groot said that what was experienced isn't out of the ordinary for the Golden State.

“What happened (Friday) and what happened (Oct. 18) is just what happens in earthquake country,” he said.