SOUTHERN CALIFORNIA
SEISMOGRAPHIC NETWORK
A Cooperative Project of
Caltech and the U.S. Geological Survey
February 20, 1997
Weekly Earthquake Report for Southern California
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February 13 - 19, 1997
Prepared by: Kate Hutton, Seismological Laboratory
(kate@bombay.gps.caltech.edu)
Lucy Jones, U. S. Geological Survey
California Institute of Technology
For further information, please contact the authors or the
Caltech Public Relations Office at 818-395-6327. For daily
updates, call our Earthquake Information Hotline: 818-395-6977.
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This week's Report covers the time period from midnight Thursday
morning, February 13, Universal Time (ie. GMT), to midnight
Wednesday night, February 19, Universal Time. In local time,
the period of coverage is from 4 p.m., February 12, Pacific
Standard Time, to 4 p.m., February 19, Pacific Standard Time.
We detected and processed 275 earthquakes during the seven-day
period covered.
There was a small resurgence of the Coso aftershocks
this week, particularly on Friday and Saturday. This activity
included a M3.8 on Friday evening and a M3.7 just after mid-
night on Saturday. All the events occured very close to the
M5.3 mainshock of last November 27. As with most of the
earthquakes in this sequence, these were strike-slip.
Aside from the Coso quakes, the largest event was a
M3.1 in the Ontario area on Saturday morning. This quake also
had a standard California strike-slip mechanism (right-lateral
on a northwest plane or left-lateral on a northeast plane).
Oddly enough, we did not get any inquiries about any
of these M3+ quakes, although a much smaller M2.3 on Tuesay,
under Claremont, was reported felt.
Table 1 lists the quakes this week that were M2.0 or
larger in the central part of the coverage area. Times are local
times; if you want Greenwich Mean Time, add 7 hrs to the Pacific
Daylight Time or 8 hrs to the Pacific Standard Time listed.
Table 1
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Date Time N Lat. W Long. Mag
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2/13 12:41 am 34 9.4 116 25.5 2.3 2 mi. NNE of Yucca Valley
2/13 11:52 am 34 54.3 116 44.1 2.5 16 mi. E of Barstow
2/13 2:52 pm 34 29.2 116 30.4 2.4 25 mi. N of Yucca Valley
2/14 3:09 am 36 58.2 117 28.9 2.7 31 mi. NW of Stovepipe
Wells
2/14 4:42 am 36 3.8 117 38.4 2.1 17 mi. E of Coso Junction
2/14 6:53 am 34 19.9 118 27.3 2.4 3 mi. NNW of San Fernando
2/14 6:56 am 32 46.4 115 27.1 2.0 6 mi. ESE of El Centro
2/14 8:33 am 36 4.5 117 39.1 2.2 16 mi. E of Coso Junction
2/14 11:01 am 34 29.5 118 3.7 2.4 6 mi. SSE of Palmdale
2/14 8:06 pm 36 4.3 117 38.3 2.9 17 mi. E of Coso Junction
2/14 8:08 pm 36 5.1 117 38.3 2.2 "
2/14 8:12 pm 36 4.5 117 38.1 2.1 "
2/14 8:16 pm 36 4.5 117 38.1 2.7 "
2/14 8:16 pm 33 14.2 116 40.5 2.3 5 mi. E of Lake Henshaw
2/14 8:22 pm 36 4.3 117 38.0 3.8 17 mi. E of Coso Junction
2/14 8:26 pm 36 4.8 117 38.1 2.0 "
2/14 8:29 pm 36 5.5 117 38.4 2.5 "
2/14 8:40 pm 36 5.0 117 38.3 2.0 "
2/14 8:59 pm 36 5.1 117 38.2 2.9 "
2/14 9:11 pm 36 4.7 117 38.3 2.6 "
2/14 11:31 pm 36 4.4 117 38.1 2.7 "
2/14 11:33 pm 36 4.7 117 38.0 2.0 "
2/15 12:06 am 36 4.8 117 38.1 2.1 "
2/15 12:13 am 36 5.1 117 38.2 3.7 "
2/15 12:23 am 36 4.6 117 38.1 2.4 "
2/15 12:27 am 36 5.1 117 38.2 2.8 "
2/15 12:40 am 36 4.6 117 38.1 2.4 "
2/15 12:55 am 36 4.3 117 38.3 2.5 "
2/15 1:33 am 36 5.0 117 38.1 2.2 "
2/15 2:43 am 36 4.6 117 37.8 2.0 "
2/15 3:35 am 36 5.2 117 38.0 2.3 "
2/15 5:12 am 33 11.3 115 36.4 2.0 2 mi. NE of Obsidian
Butte
2/15 5:36 am 36 4.2 117 38.0 2.1 17 mi. E of Coso Junction
2/15 5:40 am 36 4.9 117 37.6 2.4 18 mi. E of Coso Junction
2/15 5:40 am 34 29.8 118 3.6 2.7 6 mi. SSE of Palmdale
2/15 5:44 am 36 4.6 117 38.2 2.2 17 mi. E of Coso Junction
2/15 5:46 am 36 4.3 117 37.9 2.7 "
2/15 5:51 am 36 4.2 117 37.8 2.2 "
2/15 6:11 am 36 4.9 117 38.0 2.6 "
2/15 6:23 am 33 59.8 117 34.8 2.4 6 mi. SE of Ontario
2/15 6:57 am 36 4.7 117 38.2 2.0 17 mi. E of Coso Junction
2/15 7:14 am 33 60.0 117 34.9 3.1 5 mi. SE of Ontario
2/15 7:45 am 36 4.2 117 38.0 2.1 17 mi. E of Coso Junction
2/15 8:59 am 36 4.2 117 38.0 2.1 "
2/15 9:41 am 34 9.6 116 25.5 2.0 3 mi. NNE of Yucca Valley
2/15 12:58 pm 33 45.3 118 5.4 2.2 1 mi. NE of Seal Beach
2/15 5:26 pm 36 4.0 117 37.7 2.4 17 mi. E of Coso Junction
2/15 5:34 pm 36 3.4 117 38.0 2.0 "
2/15 8:04 pm 34 25.4 116 28.6 2.0 21 mi. N of Yucca Valley
2/15 10:06 pm 34 19.6 120 27.7 2.0 9 mi. S of Pt. Conception
2/16 6:16 am 36 4.2 117 37.9 2.1 17 mi. E of Coso Junction
2/16 7:32 am 34 21.8 119 51.6 2.0 3 mi. S of Isla Vista
2/16 2:15 pm 33 58.0 116 39.7 2.1 7 mi. SW of Morongo Valley
2/16 4:19 pm 33 20.9 116 20.7 2.0 6 mi. NNE of Borrego
Springs
2/16 10:40 pm 36 5.2 117 39.4 2.0 16 mi. E of Coso Junction
2/17 1:55 am 33 55.1 120 10.8 2.5 4 mi. WSW of Santa
Rosa Is.
2/17 2:58 pm 34 22.8 118 37.5 2.2 3 mi. WSW of Valencia
2/18 5:59 am 34 7.6 118 32.4 2.0 3 mi. SW of Encino
2/18 6:35 am 33 16.3 116 8.9 2.0 8 mi. N of Ocotillo Wells
2/18 12:56 pm 34 5.8 117 44.1 2.3 Under Claremont Colleges
FELT
2/18 5:44 pm 32 57.7 117 40.2 2.1 23 mi. SW of Oceanside
2/18 6:12 pm 32 24.0 115 11.9 2.8 25 mi. SE of Calexico
2/18 8:49 pm 33 15.7 116 0.6 2.4 2 mi. WSW of Salton City
2/19 7:57 am 36 4.0 117 38.7 2.1 17 mi. E of Coso Junction
2/19 8:00 am 33 11.4 115 33.7 2.2 4 mi. SW of Niland
2/19 12:43 pm 33 40.2 117 57.5 2.1 3 mi. S of Fountain
Valley
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