Northern California Seismicity Report for the week ending Aug 16, 2001

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 minor earthquake of magnitude 3.8, 16 miles NNW of San Simeon, CA at 02:06 PM UTC Monday, 08 13, 2001 (07:06 AM PDT Monday, Aug 13, 2001).

This quake occurred in an area that has frequent quakes above M3.5. On August 29, 1983 there was a M5.2 quake in this region, and another M5.2 on September 17, 1991. The mechanism for the quake is nearly pure reverse on an east-northeast oriented plane. A the quake generated a small aftershock sequence (4 quakes), the largest having a magnitude of 2.7. The quake was felt as far north as Monterey and as far south as San Luis Obispo. During this week there were also 2 shallow, strike-slip earthquakes above M3 at the Geysers geothermal area. They were felt by residents nearby. This activity is typical for the Geysers.

• 13 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 3.3, 2 miles S of San Juan Bautista, CA at 05:25 PM UTC Friday, 08 10, 2001 (10:25 AM PDT Friday, Aug 10, 2001).

This strike-slip quake occurred on an seismically active section the San Andreas fault.

• 7 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 2.8, 9 miles WSW of Toms Place, CA at 03:43 PM UTC Tuesday, 08 14, 2001 (08:43 AM PDT Tuesday, Aug 14, 2001).

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

2001 AUG  9 0625  5.07 39 26.22 122 57.01  7.97 29 .04  .2 1.0 BAR    2.1D  75 24 NN
2001 AUG  9 0723  9.15 37 34.54 118 51.58  6.44 33 .06  .2  .4 MOR    2.2D 101  3 NN
2001 AUG  9 2020 11.14 36 42.87 121 21.46  3.17 52 .06  .1  .2 STN    2.2D  48  1 NN
2001 AUG  9 2243 23.69 40 49.05 121 45.45 11.13 21 .08  .2 1.3 SHA    2.3D  76 25 NN
2001 AUG 10 0706  7.79 39 51.81 123 11.68  8.20 19 .14  .4  .6 BAR    2.0D  37  3 NN
 
2001 AUG 10 1142 31.31 40 24.15 124  5.05 21.87 11 .10  .4  .7 MEN    2.0D  90  4 NN
2001 AUG 10 1725 15.75 36 48.61 121 32.17  7.61 66 .13  .2  .4 SJB    3.3L  34  3 WW
2001 AUG 11 1044 10.81 35 14.90 120 55.97  3.61 13 .06  .7  .4 SSM    2.5D 190  4 WW
2001 AUG 11 1105 15.46 39 25.57 123  6.18  5.46 18 .05  .2 1.2 BAR    2.1D  76 17 WW
2001 AUG 12 1338 30.82 38 49.55 122 50.18  1.05 21 .04  .2  .5 GEY    2.2D  36  4 WW
 
2001 AUG 13 0035 48.33 38 49.09 122 50.46  3.55 43 .10  .2  .5 GEY    3.5L  27  4 WW
2001 AUG 13 0047  7.88 38 49.13 122 50.29  2.74 37 .08  .1  .8 GEY    3.3L  43  4 WW
2001 AUG 13 0927 42.53 39 48.21 123 12.44  5.86 16 .05  .2  .8 BAR    2.3D  62 10 WW
2001 AUG 13 1406  3.74 35 50.45 121 19.64  0.13 75 .10  .3 1.3 SSM  # 3.8L 173 24 WW
2001 AUG 13 1436 58.59 39 39.42 122 50.71  0.01 15 .23  .8 2.5 SAC  # 2.2D  56 11 WW
 
2001 AUG 13 1600  8.81 35 51.00 121 18.27  7.47 20 .04  .6  .8 SSM    2.1D 170  8 WW
2001 AUG 14 1351 18.15 37 28.01 118 46.99 10.90 30 .06  .4  .7 MOR    2.1D 130  6 WW
2001 AUG 14 1456  1.57 36 40.51 121 18.01  5.83 53 .05  .1  .4 STN    2.5D  38  3 WW
2001 AUG 14 1543 50.86 37 29.52 118 49.73  8.57 33 .05  .3  .8 MOR    2.8D 123  7 WW
2001 AUG 14 1703 15.68 39 40.17 122 49.56  2.76 24 .20  .4 2.2 SAC    2.5D  74 10 WW
 
2001 AUG 14 2039  4.12 38 46.63 122 43.23  1.86 15 .05  .2  .5 GEY    2.1D  54  1 WW
2001 AUG 15 0132  9.70 37 15.79 121 38.81  6.03 57 .07  .1  .4 SFL    2.3D  54 11 WW
2001 AUG 15 0219 17.39 38 23.76 122 12.72  5.89 60 .31  .3  .8 GVL    2.8D  51  6 WW
2001 AUG 15 0437 46.19 35 50.85 121 18.73  7.55 40 .07  .3  .6 SSM    2.7D 167  7 WW