earthquake.jpgOver six hours after two earthquakes rattled the Bay Area, the USGS has downgraded the magnitude of one from a 4.0 to a 3.5.

The first quake, which struck at 5:33 Monday morning, was centered near El Cerrito.

At 11:50 Monday morning, the USGS sent an alert downgrading the magnitude of that quake from 4.0 to 3.5. The USGS also originally reported that the quake had a depth of 5.7 miles, which they then revised at 5.0 miles.

The second quake struck seconds later, and was centered “roughly a quarter-mile to the northeast” of the first one (near the Mira Vista Country Club, says the Chron), or about 12 miles north northeast of SF’s City Hall.

BART was briefly held for track inspection, according to the transit agency. They experienced 5-10 minute delays as they resumed service.

I definitely felt the quakes in the Outer Sunset, where it actually rattled pictures on my wall and dishes in my cabinets (I was in the kitchen feeding the dogs, who didn’t seem to notice a thing).

According to Bay City News, folks also felt it “throughout the East Bay as far south as Hayward and as far east as Antioch and Concord, and even in peninsula cities like Redwood City.”

Appeal reader Kim says that in northern Novato, she felt a “hefty shove, followed by shaking.”

The AP reports that SFPD is saying that no damage has been reported, and that SFPD spokesperson Albie Esparza describes the quake “as a sharp jolt that woke him up.”

Those on the Golden Gate Bridge felt a “quick jolt,” a spokesperson told CBS5/KCBS.

In response to reports from some saying that they felt two quakes, not one, David Schwartz of the USGS told ABC7 broadcast Monday morning that the USGS registered a very small, magnitude 2 aftershock immediately following the initial jolt. A 1.1 magnitude aftershock also followed, but I have a hard time believing many folks felt that one.

A computer error caused the USGS website to register two 4.0 quakes in quick succession this morning, Schwartz confirmed to KRON4 broadcast at 7:07 Monday morning. However, he says that there was only one 4.0 magnitude event in the Bay Area at 5:33 this morning.

All that said, by Monday evening, the USGS was confirming that there were, indeed, two quakes.

“The first quake was a foreshock and probably magnified the effect of the second, larger earthquake,” Brad Aagaard, a research geophysicist with the USGS told the Chron.

Did you feel it? If so, tell the USGS, and then tell us!

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the author

Eve Batey is the editor and publisher of the San Francisco Appeal. She used to be the San Francisco Chronicle's Deputy Managing Editor for Online, and started at the Chronicle as their blogging and interactive editor. Before that, she was a co-founding writer and the lead editor of SFist. She's been in the city since 1997, presently living in the Outer Sunset with her husband, cat, and dog. You can reach Eve at eve@sfappeal.com.

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  • Becca Klarin

    It definitely woke me up! It felt like my apartment was rumbling on and on for a few long seconds.

  • Becca Klarin

    It definitely woke me up! It felt like my apartment was rumbling on and on for a few long seconds.

  • brad

    I think they upgraded the first quake from 2.whatever to 3.5 and the second quake is still a 4.0. That second quake was the biggest I’ve felt at our home in North Oakland and I can’t believe it was only a 3.5.

  • brad

    I think they upgraded the first quake from 2.whatever to 3.5 and the second quake is still a 4.0. That second quake was the biggest I’ve felt at our home in North Oakland and I can’t believe it was only a 3.5.