Magnitude 4.0 Earthquake Struck UC Berkeley at 2:41 PM, October 20th 2011 – 3.8 Aftershock at 8:16 PM

[Or rather, make that a 4.0 on the Richter, final answer. That was for the afternoon earthquake. This evening's aftershock at 8:16 PM was a 3.8.]

People in the West Bay could definitely feel this this one today, the one centered beneath UC Berkeley.

It felt like a succession of sharp bumps for a few seconds and then there was some generalized shaking – perhaps it all lasted about six seconds.

The Did You Feel It Map:

The initial estimate was a 4.2:

Magnitude 4.2
Date-Time
  • Thursday, October 20, 2011 at 21:41:04 UTC
  • Thursday, October 20, 2011 at 02:41:04 PM at epicenter
Location 37.864°N, 122.249°W
Depth 9.8 km (6.1 miles)
Region SAN FRANCISCO BAY AREA, CALIFORNIA
Distances
  • 2 km (2 miles) ESE (112°) from Berkeley, CA
  • 5 km (3 miles) NE (47°) from Emeryville, CA
  • 5 km (3 miles) NNW (341°) from Piedmont, CA
  • 8 km (5 miles) NNW (346°) from Oakland, CA
Location Uncertainty horizontal +/- 0.2 km (0.1 miles); depth +/- 0.4 km (0.2 miles)
Parameters Nph= 90, Dmin=2 km, Rmss=0.18 sec, Gp= 22°,
M-type=local magnitude (ML), Version=3
Source
Event ID nc71667366

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6 Responses to “Magnitude 4.0 Earthquake Struck UC Berkeley at 2:41 PM, October 20th 2011 – 3.8 Aftershock at 8:16 PM”

  1. Mary Ann Dunn says:

    296 Union St. San Francisco. 4th level. Sofa and cabinets shook for several seconds.

  2. sfcitizen says:

    Yeah, it didn’t last too long at all.

    Still, you couldn’t miss it – I thought that it would either be closer to SF or it would have a higher magnitude…

  3. margaret says:

    Quike the jolt and shaking but quick–felt hard at AltaBates Hospital
    1st floor.

  4. sfcitizen says:

    The sharpest I can recall, except for the Biggish One of 1989

  5. Nancy says:

    It was very sharp. I was sitting at my desk in my apartment and felt the whole building sway. Scared the s&*)5 out of me. Then, we had another sharp one around 8:15 which was apparently a 3. something but it was still a sharp shock. I’m wondering if I should pack my emergency suitcase.

  6. sfcitizen says:

    Yeah, I just felt the aftershock, but it seemed less severe…