Northern California Seismicity Report for the week ending Feb 19, 2004

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

• 54 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 4.4, 3 miles NE of The Geysers, CA at 08:37 PM UTC Wednesday, 02 18, 2004 (12:37 PM PST Wednesday, Feb 18, 2004).

This event was widely felt in the north Bay region. The moment tensor indicated movement on a normal fault. It was the largest event to occur at the Geysers since 9/4/1995.

• 16 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 3.0, 4 miles SW of Glen Ellen, CA at 08:24 PM UTC Monday, 02 16, 2004 (12:24 PM PST Monday, Feb 16, 2004).

This event likely occured on the Rodgers Creek fault. The mechanism was mostly right-lateral strike-slip on a fault parallel plane.
• 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 2.7, 9 miles SE of Mammoth Lakes, CA at 09:38 PM UTC Friday, 02 13, 2004 (01:38 PM PST Friday, Feb 13, 2004).

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

2004 FEB 12 0057  3.61 35 42.93 120 56.39  2.47 38 .29 1.1 6.7 SSM  # 2.5D 149 11 WW
2004 FEB 12 0927 46.77 35 35.57 120 52.79  4.18 58 .09  .2  .5 SSM    3.8L  63  6 XW
2004 FEB 12 1026 32.83 36 33.14 121  6.70  9.01 40 .05  .1  .4 PIN    2.1D  61  6 WW
2004 FEB 12 1350 10.91 35 31.70 120 47.13  0.02 36 .24  .6 4.3 SSM  # 2.3D  70 17 WW
2004 FEB 12 1612 31.24 40 14.66 124  7.25  7.03  8 .11  .8 1.1 MEN    2.7D 143  8 WW
 
2004 FEB 13 0741 22.63 36 28.26 121  2.88  5.66 39 .06  .2  .5 BIT    2.1D  57  5 NN
2004 FEB 13 0831 23.12 35 44.64 121  2.09  2.68 31 .35 1.4 5.6 SSM    2.0D 209 19 WW
2004 FEB 13 1529 42.20 35 37.38 120 56.76  0.16 29 .31 1.0 7.8 SSM  # 2.3D 118 20 WW
2004 FEB 13 1658 39.24 35 32.22 120 49.23  0.29 30 .16  .3 7.1 SSM    2.4D  73 12 WW
2004 FEB 13 1949 34.59 37 58.54 122 21.57  6.30 69 .23  .2  .5 HAY    2.6D  27  5 WW
 
2004 FEB 13 2019 27.22 40 36.88 121 52.59 16.34 12 .07  .5 1.5 SHA    2.7D 108  7 WW
2004 FEB 13 2025 26.38 40 36.84 121 53.12 15.46 16 .18  .5 2.2 SHA    2.5D  61  6 WW
2004 FEB 13 2037 25.18 35 33.05 120 51.93  6.73 32 .08  .3  .9 SSM    2.3D  75 10 WW
2004 FEB 13 2056 36.10 38 47.70 122 48.46  4.27 20 .04  .2  .4 GEY    2.3D  70  2 WW
2004 FEB 13 2117 57.94 35 33.14 120 51.87  6.87 26 .11  .3 1.2 SSM    2.1D  75 10 WW
 
2004 FEB 13 2138 28.70 37 32.53 118 52.19 10.85 40 .08  .2  .5 MOR    2.7D  97  7 II
2004 FEB 14 0449 48.39 35 32.73 120 51.22  6.09 41 .11  .2 1.1 SSM    2.5D  75 11 XX
2004 FEB 14 0547 39.44 36 56.20 121 27.83  6.90 70 .13  .2  .4 BUS    2.4D  42  5 WW
2004 FEB 14 0928 50.07 35 39.54 121  4.95  7.67 51 .09  .3  .7 SSM    2.5D 120  7 XX
2004 FEB 14 1027 51.25 38 49.10 122 47.28  2.50 15 .07  .2  .5 GEY    2.0D  77  1 WW
 
2004 FEB 14 1151  1.40 38 48.31 122 48.79  5.20 31 .07  .2  .3 GEY    2.7D  49  2 WW
2004 FEB 14 1302 55.01 37 38.19 121 41.42  7.09 56 .15  .2  .5 HAM    2.1D  76  2 WW
2004 FEB 14 1331 15.71 40 36.82 121 52.35 13.97  9 .02  .7 1.8 SHA    2.0D 109  7 WW
2004 FEB 14 1331 52.10 35 32.54 120 48.85  4.56 20 .12  .5 3.3 SSM    2.1D 117 19 WW
2004 FEB 14 1733 22.46 37 58.38 122 21.47  5.92 67 .21  .2  .4 HAY    2.4D  27  4 WW
 
2004 FEB 14 2030 14.95 35 31.72 120 48.60  4.59 49 .11  .2  .9 SSM    2.7D  74 13 XW
2004 FEB 14 2326 26.44 38 46.50 122 44.63  1.04 29 .08  .2  .4 GEY    2.9D  32  2 NN
2004 FEB 15 0036 51.75 35 31.88 120 46.84  5.20 13 .13  .6 2.4 SSM    2.0D 168 14 WW
2004 FEB 15 0141 32.39 39 24.55 123 18.43  0.02 39 .36  .6 1.9 MAA  # 3.0L  55 21 WW
2004 FEB 15 0533 36.52 35 31.74 120 50.74  6.14 21 .14  .5 5.7 SSM  # 2.0D  79 20 WW
 
2004 FEB 15 2303 10.66 35 24.29 120 40.57  0.63 33 .14  .3 4.0 SSM  # 2.4D  93 12 WW
2004 FEB 15 2307 54.14 35 39.99 121  5.51  5.31 30 .12  .3  .8 SSM    2.2D 118  6 XX
2004 FEB 16 0344 12.75 35 31.38 120 48.16  0.31 30 .26  .810.1 SSM  # 2.2D  74 17 WW
2004 FEB 16 0435 11.28 35 32.58 120 47.67  0.63 69 .40  .6 6.1 SSM  # 2.9D 101 18 WW
2004 FEB 16 1637 28.77 35 24.30 120 40.63  0.04 40 .17  .3 2.6 SSM  # 2.6D  62  3 WW
 
2004 FEB 16 1711  1.37 38 47.12 122 46.34  4.62 14 .05  .3  .6 GEY    2.2D  74  3 WW
2004 FEB 16 1838 20.95 38 48.07 122 47.95  2.25 13 .04  .2  .3 GEY    2.0D  71  1 WW
2004 FEB 16 2024 30.11 38 19.69 122 34.53  7.91 53 .13  .2  .4 ROG    3.0L  36  2 WW
2004 FEB 17 0340 17.93 35 44.15 121  3.94  0.50 36 .15  .3 4.9 SSM    3.3L 142 15 WW
2004 FEB 17 1221 55.66 38 49.45 122 45.84  3.15 13 .07  .2  .7 GEY    2.4D  74  3 WW
 
2004 FEB 17 1254 26.33 35 35.08 120 50.04  4.25 48 .10  .3  .6 SSM    2.5D  92  7 XX
2004 FEB 17 1354 26.65 35 33.74 120 49.39  7.03 36 .11  .3 1.0 SSM    2.3D  68 10 XX
2004 FEB 17 1417 48.09 35 32.74 120 51.44  5.40 31 .11  .3 2.3 SSM    2.5D  76 11 WW
2004 FEB 17 1536 21.03 38 49.16 122 50.49  3.24 25 .09  .2  .6 GEY    3.2L  73  4 WW
2004 FEB 17 1911 59.87 35 37.88 120 56.78  6.43 32 .11  .6  .6 SSM    2.4D 196  7 WW

---ORIGIN TIME (UT)--- -LAT N-- --LON W-- DEPTH  N RMS ERH ERZ LOC    PREF AZ MIN S. PAGE   2
YEAR MON DA HRMN  SEC  DEG MIN  DEG  MIN    KM  RD SEC  KM  KM REMKS  MAG  GAP DS PF

2004 FEB 17 2101 16.23 35 37.15 120 51.95  5.17 25 .16  .6 2.1 SSM    2.4D 123  2 WW
2004 FEB 17 2343 52.17 35 40.47 121  7.76  4.73 15 .12  .8  .5 SSM    2.1D 194  2 WW
2004 FEB 18 0458 34.80 35 41.66 121  3.19  0.32 39 .32  .5 7.1 SSM    2.5D 107  9 WW
2004 FEB 18 0917  7.82 38 47.47 122 46.45  1.09  9 .04  .2  .6 GEY    2.0D  77  3 WW
2004 FEB 18 1336 53.20 35 34.93 120 47.78  1.22 29 .12  .4 3.6 ROB    2.2D  93 23 WW
 
2004 FEB 18 1632 52.52 37 27.00 118 50.83  8.15 31 .08  .3 1.5 MOR    2.2D 132 12 WW
2004 FEB 18 1823 32.91 35 33.09 120 52.15  4.61 36 .15  .3 2.2 SSM    2.3D  76 10 WW
2004 FEB 18 2037 46.46 38 50.04 122 45.90  3.56 45 .14  .2  .6 GEY    4.4W  41  4 WW
2004 FEB 18 2111 16.37 35 41.45 121  1.85  7.09 28 .13  .5 1.8 SSM    2.3D  77 11 WW