Northern California Seismicity Report for the week ending Oct 09, 2003

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

• 20 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 3.9, 3 miles N of The Geysers, CA at 04:56 PM UTC Friday, 10 03, 2003 (09:56 AM PDT Friday, Oct 03, 2003).

It was preceded about a half hour ealier by a M3.6 event and followed 12 hours later by a M3.4, both in the same area as the M3.9 event. This activity was located near the northwest end of the Geysers seismogenic zone, one of the most active areas in the state with over 30,000 earthquakes located within the past 30 years, all but six smaller than M4.0.

• 15 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, 3 miles SW of Glen Ellen, CA at 07:04 AM UTC Monday, 10 06, 2003 (12:04 AM PDT Monday, Oct 06, 2003).

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

The largest event to occur this week in this region was an earthquake of magnitude 1.6, 8 miles ESE of Mammoth Lakes, CA at 10:39 PM UTC Monday, 10 06, 2003 (03:39 PM PDT Monday, Oct 06, 2003).

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

2003 OCT  2 1507 11.17 37 17.30 118 14.38 20.13 19 .14  .9 2.0 WHI    2.3D 188 16 WW
2003 OCT  2 1550 26.93 37 15.23 118 13.41 11.73 35 .07  .8 1.2 DEV    2.8D 189 13 WW
2003 OCT  2 1617 42.91 37 15.22 118 13.57 12.85 36 .06  .8 1.0 DEV    2.8D 188 13 WW
2003 OCT  2 1716 35.98 37 15.33 118 13.76 13.66 43 .09  .5  .6 WHI    3.0D 160 13 II
2003 OCT  3 0412 12.59 40 21.62 124 14.47 24.66 10 .12  .9 1.4 MEN    2.2D 123 12 XX
 
2003 OCT  3 1628 28.48 38 50.02 122 48.89  2.60 48 .09  .1 1.0 GEY    3.6L  42  6 NW
2003 OCT  3 1628 56.08 38 49.27 122 49.64  0.03 15 .07  .3  .9 GEY  #       91  6 NN
2003 OCT  3 1644 22.88 38 50.78 122 48.09  3.61 28 .05  .2 1.1 GEY    2.5D  41  6 NN
2003 OCT  3 1656 34.89 38 50.45 122 48.62  2.54 43 .08  .1  .8 GEY    3.9L  42  6 NW
2003 OCT  4 0502 28.62 38 49.07 122 48.61  5.01 33 .05  .1  .4 GEY    3.4L  42  7 WW
 
2003 OCT  4 0551  6.34 38 48.92 122 48.86  4.87 36 .03  .1  .4 GEY    2.6D  39  6 NN
2003 OCT  4 2139  2.74 37 27.97 121 49.19  7.34 57 .05  .1  .3 MIS    2.0D  28  2 NN
2003 OCT  5 1515 37.53 39 18.34 122 48.59  0.99 18 .18  .614.5 BAR  - 2.2D 134 18 WW
2003 OCT  6 0704 18.24 38 19.91 122 34.31 10.27 63 .11  .2  .3 ROG    2.5D  27  2 AN
2003 OCT  6 2245  5.12 37 15.46 118 13.83 13.08 30 .09  .7  .5 WHI    2.2D 160 12 II
 
2003 OCT  7 0734 18.64 37 15.81 118 13.93 13.72 42 .09  .6  .4 WHI    2.6D 157 12 II
2003 OCT  8 0440 10.99 39 32.91 123 22.05  1.16 11 .09  .4 3.9 MAA    2.4D  85 23 WW
2003 OCT  8 0441  4.88 39 33.06 123 22.35 10.73 18 .08  .2  .6 MAA    2.5D  86 11 WW
2003 OCT  8 0717  4.92 40 25.26 124 27.35 22.39  9 .02  .9  .6 MEN    2.3D 234 23 WW
2003 OCT  8 0914 54.01 36 28.25 121  2.80  5.58 37 .06  .2  .5 BIT    2.2D  57  5 WW