California Seismicity Report for the week

Northern California Seismicity Report for the week ending Feb 26, 2009

This report provides a brief summary of earthquake activity recorded by the U.S. Geological Survey Northern California Seismic Network in Menlo Park and the University of California Berkeley Seismological Laboratory. It is automatically generated each Wednesday shortly after midnight, Universal time (UT). UT (ie., Greenwich Mean Time) is 8 hours ahead of PST or 7 hours ahead of PDT.

Because it is not possible to review all of the earthquakes before this report is generated, it may contain errors. Please report errors or provide suggestions and comments to ncsn@andreas.wr.usgs.gov

Information about seismicity for other regions is available from the U.S. Geological Survey Earthquake Hazards Program Website. In addition, all earthquake data can be retrieved from the Northern California Earthquake Data Center.

Please note that some of the earthquake data in this report have been reviewed by seismic analysts. Consequently, the parameters that describe the hypocenter, magnitude, origin time, and solution statistics may differ slightly from the information provided at the Northern California Maps of Recent Earthquake Activity website. The differences reflect revised arrival times at seismic stations and the analysts' decisions to include or exclude information from seismic stations.

The minimum magnitude ( M) values in the following bullets reflect the smallest earthquake which the network can routinely record within the region. During the previous seven-day period ending at midnight (UT) Wednesday, our seismic networks recorded

• 30 M >2.0 earthquakes in Northern and Central California (map) (within dashed polygon of figure).

The largest event to occur this week in this region was a minor earthquake of magnitude 3.7, 1 miles N of The Geysers, CA at 10:29 AM UTC Friday, 02 20, 2009 (02:29 AM PST Friday, Feb 20, 2009).

• 19 M >1.2 earthquakes in the San Francisco Bay area (map).

The largest event to occur this week in this region was a minor earthquake of magnitude 3.2, 4 miles ENE of Union City, CA at 07:01 PM UTC Saturday, 02 21, 2009 (11:01 AM PST Saturday, Feb 21, 2009).

• 5 M >1.2 earthquakes in the Long Valley region (map).

The largest event to occur this week in this region was a microearthquake of magnitude 1.5, 10 miles WSW of Toms Place, CA at 05:16 AM UTC Saturday, 02 21, 2009 (09:16 PM PST Friday, Feb 20, 2009).

The following table provides a listing of all M >2 earthquakes that occurred this week. An explanation of the entries in the table is available.

---ORIGIN TIME (UT)--- -LAT N-- --LON W-- DEPTH  N RMS ERH ERZ LOC    PREF AZ MIN S. PAGE   1
YEAR MON DA HRMN  SEC  DEG MIN  DEG  MIN    KM  RD SEC  KM  KM REMKS  MAG  GAP DS PF

2009 FEB 19 0026 22.92 39 14.47 123 19.60  4.03 18 .05  .2  .8        2.3D  55  5  
2009 FEB 19 0028 43.51 36 41.02 121 18.67  5.08 69 .07  .1  .3        2.9D  53  4  
2009 FEB 19 0244  4.74 39 14.20 123 19.58  4.53 22 .07  .2  .7        2.0D  58  4  
2009 FEB 19 0449 43.05 38 48.85 122 48.44  2.75 43 .05  .1  .2        2.3D  35  1  
2009 FEB 19 1727 39.69 39 14.01 123 19.89  6.70 19 .12  .4  .4        2.4D 175 27  

2009 FEB 19 2142  1.59 36 52.00 121 35.90  5.06 53 .10  .2  .3        2.2D  50  2  
2009 FEB 20 0226  2.92 36 41.52 121 19.80  7.08 55 .06  .1  .4        2.3D  38  6  
2009 FEB 20 0621  1.24 36 51.58 121 35.88  6.58 72 .08  .2  .3        2.7D  54  3  
2009 FEB 20 1029 27.61 38 48.62 122 48.58  2.30 65 .08  .1  .2        3.7W  22  1  
2009 FEB 20 2241 17.81 40 29.11 124 16.86 20.24 13 .06  .4  .3        2.4D 118  5  

2009 FEB 20 2251 53.48 38 47.53 122 44.73  2.41 64 .07  .1  .2        2.8D  27  2  
2009 FEB 21 0519 22.81 38 49.38 122 49.49  2.51 44 .06  .2  .2        2.1D  35  1  
2009 FEB 21 0843 23.18 36 19.33 120 22.10 11.83 77 .15  .2  .4        2.8D  78  8  
2009 FEB 21 1051 41.95 36 35.04 121 10.88  5.23 58 .06  .1  .3        2.7D  33  1  
2009 FEB 21 1158 44.02 38 47.14 122 43.58  2.09 48 .07  .2  .2        2.4D  37  1  

2009 FEB 21 1527  6.91 36 25.72 120 57.26  8.14 77 .10  .2  .5        3.2W  60 13  
2009 FEB 21 1901  2.54 37 37.57 121 57.00 11.79159 .22  .2  .4        3.2L  13  2  
2009 FEB 21 2123 28.45 36 40.37 121 17.81  4.62 43 .05  .1  .3        2.0D  66  2  
2009 FEB 21 2226 39.99 38 50.26 122 49.57  2.04 45 .06  .1  .2        2.1D  38  1  
2009 FEB 21 2359 27.68 36 32.65 121  3.75  8.30 46 .08  .1  .3        2.4D  55  4  

2009 FEB 22 0249 34.72 39 29.89 123  6.97  5.74 24 .10  .2  .8        2.3D  47  9  
2009 FEB 22 0811 57.92 38 49.49 122 49.69  2.39 49 .06  .1  .2        2.5D  35  1  
2009 FEB 22 1332 57.56 36 35.76 120 20.10 14.59 39 .22  .5  .7        2.1D 130 21  
2009 FEB 22 1709 53.80 39 23.78 123 18.00  4.46 21 .06  .2 2.0        2.3D  63 21  
2009 FEB 22 1916 35.00 39  0.45 123 39.90  5.92 35 .12  .3  .4        3.1L 225 11  

2009 FEB 23 1847  4.79 38 49.09 122 48.86  3.39 38 .08  .2  .3        2.2D  41  1  
2009 FEB 24 0059 25.33 38 46.17 122 44.52  2.58 59 .07  .1  .2        2.5D  37  2  
2009 FEB 24 0535  8.98 38 47.46 122 46.27  4.42 47 .06  .2  .2        2.0D  44  1  
2009 FEB 24 1353 44.38 37 39.12 121 48.91 14.70 65 .15  .2  .3        2.5D  34  4  
2009 FEB 25 0254 12.32 36 56.09 121 25.88  6.64 72 .08  .1  .3        2.3D  45  6   
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Southern California Earthquakes in the Past Week

Anthony Guarino
Seismological Laboratory
Sue Hough U. S. Geological Survey
California Institute of Technology

February 26, 2009

This report covers the seven day period ending 16:00 on February 26, 2009. During this period we detected and analyzed 228 earthquakes.
The table below lists the quakes during the past 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.

Mag. PST Date   PST Time  Lat.       Long.    Depth  Descriptive location
-------------------------------------------------------------------------------------------

10377693 3.7 2009/02/20 04:19:14 35 59.0 N 117 18.3 W 1.9 25 km (15 mi) NNE of Trona, CA
Felt near Trona and surrounding area
10377713 2.7 2009/02/20 05:54:40 32 22.9 N 115 17.4 W 6.0 37 km (23 mi) SSE of Calexico, CA
10377721 2.1 2009/02/20 06:41:56 35 58.8 N 117 18.3 W 0.0 24 km (15 mi) NNE of Trona, CA
10377765 2.4 2009/02/20 10:55:04 34 49.5 N 118 57.3 W 14.3 1 km ( 1 mi) NW of Frazier Park, CA
Felt at Frazier Park
10377889 2.3 2009/02/20 22:19:13 36 50.8 N 117 44.0 W 8.1 40 km (25 mi) NE of Lone Pine, CA
10377989 2.1 2009/02/21 10:13:47 35 58.2 N 117 18.9 W 0.9 23 km (14 mi) NNE of Trona, CA
10378005 2.4 2009/02/21 12:04:19 33 38.3 N 116 42.9 W 17.4 10 km ( 6 mi) NNW of Anza, CA
10378141 2.1 2009/02/22 04:21:45 33 31.0 N 116 28.4 W 8.9 19 km (12 mi) ESE of Anza, CA
10378181 3.2 2009/02/22 10:13:43 34 34.6 N 121 33.0 W 6.0 82 km (51 mi) W of Pt. Arguello, CA
10378305 2.3 2009/02/23 04:33:46 36 12.5 N 117 54.9 W 0.0 11 km ( 7 mi) SE of Olancha, CA
10378365 2.7 2009/02/23 06:53:28 32 10.7 N 115 51.3 W 6.0 63 km (39 mi) SSE of Ocotillo, CA
10378421 2.3 2009/02/23 14:55:49 34 39.3 N 116 17.0 W 3.1 58 km (36 mi) N of Joshua Tree, CA
10378473 3.2 2009/02/23 22:07:27 32 7.9 N 115 45.1 W 6.0 64 km (40 mi) SSW of Calexico, CA
10378545 2.0 2009/02/24 13:34:14 34 56.5 N 119 5.2 W 14.6 14 km ( 9 mi) W of Grapevine, CA
10378601 2.0 2009/02/24 19:25:07 32 9.9 N 115 17.3 W 6.0 59 km (37 mi) SSE of Calexico, CA
10378733 2.2 2009/02/25 16:03:33 34 8.1 N 116 50.7 W 11.7 4 km ( 3 mi) NNW of Mt. San Gorgonio, CA
10378773 2.0 2009/02/25 20:55:51 33 40.2 N 116 41.7 W 17.0 8 km ( 5 mi) SSE of Idyllwild, CA
10378869 2.6 2009/02/26 14:50:11 35 19.7 N 118 34.2 W 3.8 25 km (15 mi) NNW of Tehachapi, CA
Felt near Tehachapi