Posts Tagged ‘richtor’

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

Thursday, October 20th, 2011

[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

A Moderate Earthquake Just Hit San Francisco – Thursday, January 7th 2010 at 10:09 AM

Thursday, January 7th, 2010

It felt like a quick initial jolt followed up by three seconds of shaking to those of us in San Francisco. See what people thought about the latest rumblings of our San Andreas Fault over at SFist.com.

The updated report from the USGS indicates a 4.2 near the city of Milpitas.

Right here, “A” marks the spot:

A light earthquake occurred at 10:09:35 AM (PST) on Thursday, January 7, 2010.
The magnitude 4.2 event occurred 10 km (6 miles) ENE of Milpitas, CA.
The hypocentral depth is 9 km ( 6 miles).


Magnitude 4.2 – local magnitude (ML)
Time Thursday, January 7, 2010 at 10:09:35 AM (PST)
Thursday, January 7, 2010 at 18:09:35 (UTC)
Distance from Milpitas, CA – 10 km (6 miles) ENE (62 degrees)
Alum Rock, CA – 12 km (8 miles) NNE (12 degrees)
Sunol, CA – 16 km (10 miles) SSE (150 degrees)
San Jose City Hall, CA – 17 km (11 miles) NNE (29 degrees)
Coordinates 37 deg. 28.6 min. N (37.477N), 121 deg. 47.8 min. W (121.797W)
Depth 9 km (5.6 miles)
Location Quality Excellent
Location Quality Parameters Nst= 89, Nph= 89, Dmin=3 km, Rmss=0.08 sec, Erho=0.1 km, Erzz=0.4 km, Gp=36 degrees
Event ID# nc71336726
Additional Information map with fault names
Google Earth KML (Requires Google Earth.)
ShakeMap shaking intensity maps
NCSS First Motion Mechanism 1

As per usual, t’was the Northern Calaveras (it means “skulls”) branch of the San Andreas. Alum Rock, will you ever win?