Special Reports
More aftershocks strike Simi Valley

Seismo-Watch More Special Earthquake Reports

Wednesday, January 30, 2002

Aftershock continued to strike the northwestern Los Angeles suburbs in the days following the Monday, January 28, Simi Valley M4.2 earthquake.

Of the 29 aftershocks measuring M2.0+, six have registered in the M3 range. The largest aftershocks measured M3.9 and M3.8 and occurred minutes following the main M4.2 shock. See list below.

See a clip of the NBC4 Seis-Cam showing part of the Simi Valley earthquake series.

Two other quakes measured in the mid M3 range, a M3.6 at 12:23 p.m. PST on Tuesday, January 29, and a M3.5 at 10:48 a.m. PST on Wednesday, January 30. Both of these quakes were followed by a smaller M3 within 10 minutes and it is this multiple-tremor sequence that has caused people to become concerned.

Although the activity is centered in a relatively unpopulated area of the western Santa Susana Mountains, near the Los Angeles-Ventura County line, many nearby communities have dense populations and suggest the tremors were felt by hundreds of thousands of people. Did you feel the quakes?

None of the aftershocks have been strong enough to topple items from tables or shelves. The main shock was probably just strong enough to knock things over but nothing has been reported.

Windows are said to have jiggled, walls vibrated, things rattled, and some reported low groan-like sounds coming from the earth. Some items in office buildings apparently shook, causing sounds that alerted workers to the quake.

While the shaking has startled many and even frightened others, some have become thrilled and others excited. Some didn't know they happened till someone told them.

Emergency services organizations have used the tremors to run tests on their response in the event of a major earthquake.

More information will be added as it becomes available. Check back later and subscribe to the EQ Flash! Alert Bulletin service for automatic notification of the quakes.

Here is a list of aftershocks thus far:
Events in red denote M3s and blue denote M4s.

GREENWICH MEAN TIME (MINUS 8 HRS FOR PST)
DATE      TIME       LAT      LONG    DEP  MAG QUAL  LOCATION
02/01/29 05:53:08  34.35N 118.65W  13.0 3.1 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 05:53:28  34.36N 118.66W  14.2 4.2 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:00:39  34.37N 118.67W  14.2 3.9 ML  A    7 mi. NNE of Simi Valley, CA
02/01/29 06:08:01  34.37N 118.66W  14.4 3.8 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:09:09  34.36N 118.67W  14.9 2.8 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:12:05  34.36N 118.66W  14.2 2.8 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:15:15  34.37N 118.67W  14.0 2.3 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:20:55  34.36N 118.67W  15.0 2.1 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:26:31  34.36N 118.65W  13.2 2.9 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:28:13  34.36N 118.66W  15.1 2.4 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 06:44:23  34.36N 118.67W  14.4 2.0 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 10:21:21  34.36N 118.67W  15.2 2.4 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 10:58:42  34.36N 118.68W  13.3 2.1 ML  A    5 mi. NNE of Simi Valley, CA
02/01/29 15:42:14  34.36N 118.66W  14.8 2.4 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 19:20:54  34.36N 118.67W  11.8 2.7 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 20:23:07  34.36N 118.67W  12.6 3.6 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 20:25:11  34.36N 118.66W  13.1 2.4 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 20:27:27  34.37N 118.66W  13.1 3.1 ML  A    7 mi. NNE of Simi Valley, CA
02/01/29 20:32:49  34.36N 118.67W  14.8 2.2 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 21:10:58  34.36N 118.67W  14.2 2.5 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 23:07:15  34.36N 118.66W  12.6 2.2 ML  A    6 mi. NNE of Simi Valley, CA
02/01/29 23:28:39  34.37N 118.66W  13.2 2.2 ML  A    7 mi. NNE of Simi Valley, CA
02/01/30 02:34:44  34.36N 118.68W  15.4 2.7 ML  A*   6 mi. N   of Simi Valley, CA
02/01/30 07:53:34  34.37N 118.68W  12.9 2.2 ML  A    6 mi. NNE of Simi Valley, CA
02/01/30 13:46:22  34.36N 118.67W  13.7 2.3 ML  A    6 mi. NNE of Simi Valley, CA
02/01/30 18:47:57  34.37N 118.66W  11.7 3.5 ML  A    6 mi. NNE of Simi Valley, CA
02/01/30 18:57:58  34.36N 118.68W  12.1 3.0 ML  A*   6 mi. NNE of Simi Valley, CA
02/01/30 19:00:44  34.36N 118.68W  13.5 2.2ML  A    6 mi. NNE of Simi Valley, CA
Report update: 9:05:37 AM, Saturday, February 9, 2002
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