Northern California Seismicity Report for the week ending Dec 28, 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

• 41 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 offshore earthquake of magnitude 4.0, 12 miles SW of Ferndale, CA at 01:15 PM UTC Wednesday, 12 27, 2000 (05:15 AM PST Wednesday, Dec 27, 2000). The event was weakly felt throughout the Cape Mendocino area. A M3.3 earthquake occurred last Thursday afternoon about seven miles north of Burney and 45 miles northeast of Redding (04:38 PM PST Thursday, Dec 21, 2000; 00:38 AM UTC Friday, Dec 22, 2000). This event was an aftershock to a M3.6 event earlier that afternoon and the largest of eight M>2 aftershocks that have been recorded here in the past week.

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

The largest event to occur this week in this region was a microearthquake of magnitude 2.5, 5 miles NE of Gilroy, CA at 04:40 AM UTC Sunday, 12 24, 2000 (08:40 PM PST Saturday, Dec 23, 2000).

• 22 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, 8 miles W of Toms Place, CA at 04:57 AM UTC Thursday, 12 21, 2000 (08:57 PM PST Wednesday, Dec 20, 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 21 0007 52.87 40 58.72 121 42.01 14.12 21 .27  .8 5.2 SHA    2.2D  80 28 NN
2000 DEC 21 0010 35.57 40 58.86 121 41.42  4.98  9 .07  .4 8.6 SHA  - 2.3D  83 28 WW
2000 DEC 21 0038  3.14 40 59.06 121 42.03  4.59 43 .30  .3 8.3 SHA  # 3.3D  77 28 NN
2000 DEC 21 0046 16.01 40 59.22 121 41.54 13.43 16 .12  .4 2.3 SHA    2.6D 122 27 WW
2000 DEC 21 0126 29.15 40 59.81 121 41.71 13.08 27 .19  .4 2.2 SHA    3.1D  77 26 WW
 
2000 DEC 21 0154  1.06 40 59.12 121 40.56  7.37 17 .11  .4 5.1 SHA    2.3D  84 26 WW
2000 DEC 21 0233 57.32 40 59.51 121 41.06 10.60 25 .09  .2 1.9 SHA    2.8D  79 26 NN
2000 DEC 21 0457 27.35 37 32.85 118 49.67  8.87 32 .07  .3  .6 MOR    3.3D 114  5 NN
2000 DEC 21 0457 29.35 40 58.93 121 41.55  7.81 12 .14  .6 6.2 SHA    2.4D  81 28 WW
2000 DEC 21 0529 52.14 40 59.32 121 40.88  2.56 21 .14  .411.9 SHA  - 2.5D  80 26 WW
 
2000 DEC 21 0611 25.30 40 58.60 121 41.76 18.41 17 .11  .8 2.4 SHA    2.2D 165 43 NN
2000 DEC 21 0727  5.17 38 59.03 123  4.23  8.04 30 .07  .2  .5 MAA    2.5D  34  8 WW
2000 DEC 22 0452 12.55 40 58.76 121 41.53  3.69 21 .21  .414.6 SHA  - 2.7D  81 28 WW
2000 DEC 22 1850 58.53 40 58.71 121 40.59  4.01 15 .08  .4 9.7 SHA  - 2.5D  84 27 NN
2000 DEC 22 2249 48.62 39 23.56 123  3.39  4.78 30 .04  .1 1.0 BAR    2.0D  57 16 NN
 
2000 DEC 22 2358  0.21 36  4.52 120 38.33  6.10 52 .09  .2  .3 SLA    2.7D  65  4 NN
2000 DEC 23 0410  2.18 40 58.42 121 40.74  4.99 13 .06  .3 7.7 SHA  - 2.2D  83 28 NN
2000 DEC 23 0444  4.09 40 58.47 121 40.88  6.78 21 .07  .2 3.8 SHA    2.4D  83 28 NN
2000 DEC 23 0751 12.92 40 59.23 121 40.48  5.03  9 .06  .5 7.8 SHA  - 2.3D 176 26 WW
2000 DEC 23 1257  4.27 38 47.10 122 28.34  7.14 38 .21  .3  .5 GVL    2.1D  44  3 NN
 
2000 DEC 23 1629  0.08 37 33.10 118 49.62  8.91 36 .07  .3  .6 MOR    2.6D 106  4 NN
2000 DEC 23 1824 20.85 38 51.06 122 48.36  1.46 17 .05  .2  .6 GEY    2.4D  44  5 WW
2000 DEC 23 2348 53.58 39 23.37 123  3.14  1.66 20 .05  .2 2.9 BAR    2.3D  80 16 WW
2000 DEC 24 0250 43.47 40 59.42 121 40.82  8.01 25 .09  .2 2.9 SHA    2.9D  84 26 NN
2000 DEC 24 0309 44.67 40 59.28 121 40.90  4.98 10 .09  .5 9.7 SHA  - 2.1D  91 26 WW
 
2000 DEC 24 0440 47.81 37  3.15 121 29.33  6.67 73 .06  .1  .3 CYS    2.5D  50  3 NN
2000 DEC 24 1144 15.29 40 58.57 121 39.98  4.96  9 .05  .5 7.2 SHA  - 2.3D 180 27 WW
2000 DEC 24 1144 15.29 40 58.57 121 39.98  4.96  9 .05  .5 7.2 SHA  - 2.3D 180 27 WW
2000 DEC 24 1346 28.93 38 46.78 122 42.89  2.67 14 .05  .2  .4 GEY    2.1D  85  1 WW
2000 DEC 24 1419 18.32 40 21.37 124 15.83 29.31 14 .11 1.0 1.7 MEN    2.6D 138 13 WW
 
2000 DEC 24 2212 22.09 37 52.73 122 14.93  9.00 44 .07  .2  .4 HAY    2.2D  50  2 WW
2000 DEC 24 2334 49.10 37 28.37 118 50.71  4.78 33 .07  .3 1.0 MOR    2.0D 130 11 WW
2000 DEC 25 1057 23.87 37 52.24 122 14.51  9.80 37 .07  .2  .4 HAY    2.0D  47  2 WW
2000 DEC 25 1845 23.73 39 30.58 123 23.85  3.77 16 .08  .3 2.9 MAA    2.1D  93 11 WW
2000 DEC 25 1855 38.21 37 52.74 122 14.84  9.43 45 .08  .1  .4 HAY    2.2D  47  2 WW
 
2000 DEC 26 0103 21.13 37 28.78 121 48.96  6.55 46 .07  .1  .4 MIS    2.1D  60  4 WW
2000 DEC 26 0711 11.98 37 25.95 118 34.24 12.38 24 .05  .3 1.0 RVL    2.2D 111 15 WW
2000 DEC 26 0842 29.42 38 46.34 122 44.67  1.21 20 .07  .2  .5 GEY    2.3D  38  2 WW
2000 DEC 26 1813 49.25 38 48.27 122 46.23  2.56 21 .05  .2  .5 GEY    2.2D  44  2 WW
2000 DEC 27 0900 16.98 38 48.68 122 47.70  4.84 24 .04  .2  .4 GEY    2.1D  48  0 WW
 
2000 DEC 27 1315 11.35 40 28.09 124 26.81 28.72 39 .07  .6  .4 MEN    4.0L 224  9 WW