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@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
The largest event to occur this week in this region was a light earthquake of magnitude 4.3 10 miles SSE of Tres Pinos, CA at 08:48 AM UTC Monday, Jan 18, 1999 (12:48 AM PST Monday, Jan 18, 1999).
The largest event to occur this week in this region was a microearthquake of magnitude 2.2 8 miles N of Morgan Hill, CA at 10:12 AM UTC Saturday, Jan 16, 1999 (02:12 AM PST Saturday, Jan 16, 1999).
The largest event to occur this week in this region was a microearthquake of magnitude 2.7 6 miles E of Mammoth Lakes, CA at 04:34 AM UTC Friday, Jan 15, 1999 (08:34 PM PST Thursday, Jan 14, 1999).
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 N RMS ERH ERZ LOC PREF YR MON DA HRMN SEC DEG MIN DEG MIN KM RD S SEC KM KM REMKS MAG 99 JAN 14 757 10.49 36 1.83 121 34.67 5.86 65 1 .06 .2 .5 SUR 2.7D 99 JAN 14 1336 16.72 38 49.21 122 47.85 4.40 41 1 .04 .1 .3 GEY 2.6D 99 JAN 14 1923 13.92 37 32.31 118 48.81 4.94 26 .06 .3 .6 MOR 2.4D 99 JAN 15 101 20.87 38 48.64 122 45.28 1.67 22 .07 .2 .5 GEY 2.2D 99 JAN 15 407 49.95 37 38.92 118 51.10 5.57 29 .07 .3 .4 HCF 2.5D 99 JAN 15 434 28.19 37 38.68 118 51.30 6.18 30 .07 .3 .4 SMO 2.7D 99 JAN 15 502 6.19 37 39.06 118 50.67 6.20 19 .04 .3 .4 HCF 2.4D 99 JAN 15 612 4.84 37 38.90 118 51.17 5.41 28 .07 .3 .4 HCF 2.6D 99 JAN 15 1635 21.02 40 38.12 122 24.62 23.78 16 1 .09 .3 .7 SHA 3.1D 99 JAN 16 856 25.70 38 46.19 122 27.75 6.84 35 1 .16 .2 .5 GVL 2.3D 99 JAN 16 1012 1.40 37 14.52 121 37.73 6.00 90 3 .06 .1 .2 SFL 2.2D 99 JAN 16 2303 34.02 38 47.32 122 46.53 3.07 24 .05 .2 .5 GEY 2.1D 99 JAN 17 534 9.97 40 38.53 122 24.45 24.23 12 .06 .4 .7 SHA 2.6D 99 JAN 17 2023 23.32 40 11.47 121 2.95 7.02 13 .11 .6 1.9 ALM 2.2D 99 JAN 18 16 20.21 36 48.33 121 31.15 5.52 60 .11 .2 .4 SJB 1.6D 99 JAN 18 848 36.70 36 38.81 121 16.06 10.98 76 2 .08 .1 .2 STN 4.3L 99 JAN 18 1325 47.23 35 47.99 121 8.31 5.35 42 .04 .2 .5 SSM 2.8D 99 JAN 18 2134 47.40 36 38.88 121 16.19 10.12 72 2 .06 .1 .2 STN 3.3D 99 JAN 18 2226 28.65 38 49.62 122 47.99 4.44 42 1 .05 .1 .3 GEY 2.6D 99 JAN 19 201 56.18 41 38.47 124 9.87 4.00 8 .07 1.6 7.5 DEL - 2.5D 99 JAN 19 306 41.39 36 39.28 121 16.78 10.18 52 .05 .1 .4 STN 2.2D 99 JAN 19 803 50.30 36 44.69 121 25.89 6.73 67 4 .12 .1 .3 SJB 2.9D 99 JAN 19 1428 35.64 40 19.67 121 59.72 13.69 15 2 .07 .4 1.3 SHA 2.5D 99 JAN 19 1612 19.15 39 36.88 121 10.15 11.18 10 2 .12 .7 4.5 WAK 2.4D 99 JAN 19 1741 0.17 38 51.03 122 49.23 1.35 14 .05 .2 .7 GEY 2.1D 99 JAN 19 2148 14.56 40 20.32 121 59.01 21.26 9 .05 .4 2.2 SHA 2.1D 99 JAN 20 1708 49.51 40 38.07 122 25.08 23.81 12 .14 .6 1.1 SHA 2.5D 99 JAN 20 2136 30.71 38 44.70 122 43.00 2.09 16 .08 .3 .6 NAP 2.4D 99 JAN 20 2343 16.84 39 43.49 122 6.62 18.75 23 .20 .8 .9 SAC 2.6D
