Northern California Seismicity Report for the week ending Dec 14, 2000

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

The report no longer includes maps showing earthquakes for the entire US or world. Those maps are now available from the U.S.G.S. National Earthquake Information Center. 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 contained on the real-time earthquake web page. 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

• 24 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 light earthquake of magnitude 4.2, 2 miles ESE of The Geysers, CA at 07:41 AM UTC Friday, 12 08, 2000 (11:41 PM PST Thursday, Dec 07, 2000).

This recent earthquake occurred in the Geysers geothermal area, one of the most seismically active regions in California. We have had 2 magnitude 4.0 or larger quakes in this geothermal region this year, and 4 magnitude 3.0 or larger earthquakes. In the last decade we have recorded nearly 40 magnitude 3.0 or larger quakes in the region, and we expect more in the future. Earthquakes of the size that occurred last Friday are typical of the largest we see in the area. Because of the complex nature of the faulting in this region the earthquakes are scattered over several square miles, forming a somewhat diffuse pattern of seismicity.

• 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 3.4, 4 miles WNW of San Juan Bautista, CA at 10:08 PM UTC Tuesday, 12 12, 2000 (02:08 PM PST Tuesday, Dec 12, 2000).

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

The largest event to occur this week in this region was a minor earthquake of magnitude 3.3, 10 miles WSW of Toms Place, CA at 09:25 PM UTC Tuesday, 12 12, 2000 (01:25 PM PST Tuesday, Dec 12, 2000).

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

2000 DEC  7 1501 47.79 37 26.34 121 48.29  4.46 61 .06  .1  .2 ALU    2.2D  53  1 NN
2000 DEC  7 1537 26.01 36 14.70 120 48.12  7.14 51 .08  .2  .3 BIT    2.9D  81  3 NN
2000 DEC  7 2259 47.29 41  3.48 123 19.09 35.30 14 .05  .4 1.6 KLA  # 2.3D  96 27 NN
2000 DEC  8 0317 49.61 37 17.80 121 40.61  3.11 60 .06  .1  .3 SFL    2.2D  49  4 NN
2000 DEC  8 0507 35.21 38 54.94 123  0.85  6.07 28 .07  .2  .6 MAA    2.1D  31 10 NN
 
2000 DEC  8 0741 11.43 38 46.92 122 45.99  4.08 50 .10  .2  .4 GEY    4.2L  30  4 NN
2000 DEC  8 0750  3.99 38 48.71 122 46.43  3.89 20 .06  .2  .4 GEY    2.1D  81  2 NN
2000 DEC  8 1601 45.94 38 45.53 122 26.96  6.29 17 .08  .4  .5 GVL    2.0D  63  5 NN
2000 DEC 10 0021 16.51 38 50.82 122 46.83  1.93 35 .05  .1  .4 GEY    2.2D  37  5 NN
2000 DEC 10 0507 20.43 35 47.82 121 29.40  0.56 48 .07  .2 1.9 SSM    2.1D 196 16 NN
 
2000 DEC 10 1001 18.54 40 13.58 123 39.28 28.95 22 .06  .2  .6 MEN    2.2D  86 17 NN
2000 DEC 11 0656 58.36 40 37.85 122 23.83 23.66  9 .07  .5  .7 SHA    2.1D  77 11 NN
2000 DEC 11 0857 36.64 37 30.75 118 47.74 10.41 30 .06  .4  .7 MOR    2.2D 135  7 NN
2000 DEC 12 0149 46.71 37 30.96 118 47.69  9.97 28 .07  .3  .8 MOR    2.2D 115  7 WW
2000 DEC 12 0509 36.82 38 49.71 122 45.67  1.87 39 .08  .1  .4 GEY    2.9D  48  4 NN
 
2000 DEC 12 0613 35.29 38 48.41 122 46.50  0.08 18 .09  .2  .6 GEY  # 2.2D  43  2 WW
2000 DEC 12 1557 38.33 38 48.45 122 46.42  0.18 17 .04  .2  .6 GEY    2.0D  44  2 WW
2000 DEC 12 2001 34.11 36 35.31 121  6.16  8.16 55 .11  .2  .3 BVL    3.0D  38  6 WW
2000 DEC 12 2018 43.55 36 35.10 121  6.30  7.15 42 .08  .2  .4 BVL    2.2D  36  6 WW
2000 DEC 12 2125 28.75 37 29.12 118 50.23  5.35 24 .07  .3 1.8 MOR    3.3D 124 18 WW
 
2000 DEC 12 2208 11.42 36 51.91 121 36.01  7.17 68 .11  .2  .3 SJB    3.4D  51  2 WW
2000 DEC 13 1439 23.03 37 33.03 118 53.10  7.98 33 .06  .3  .6 MOR    2.4D 106  7 WW
2000 DEC 13 1524 15.11 37 24.61 121 45.41  8.58 61 .05  .1  .4 ALU    2.4D  60  6 WW
2000 DEC 13 1607 19.60 40 41.17 123 46.49 23.62 10 .05  .5  .8 EUR    2.0D 144 21 WW