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 minor earthquake of magnitude 3.2 9 miles SE of Mammoth Lakes, CA at 02:55 AM UTC Monday, May 03, 1999 (07:55 PM PDT Sunday, May 02, 1999).
The largest event to occur this week in this region was a microearthquake of magnitude 2.1 2 miles SSE of San Juan Bautista, CA at 03:29 AM UTC Saturday, May 01, 1999 (08:29 PM PDT Friday, Apr 30, 1999).
In addition to the above quake, a M3.1 earthquake occurred about 43 km (27 miles) offshore of Pt Reyes on 05/02/99 at 05:59 UTC. This is an unusual earthquake, as there are no recorded quakes of this size since 1969. The event may have occurred on one of the mapped thrust faults east of the San Andreas fault, but the data are insufficient to compute a reliable focal mechanism.
The largest event to occur this week in this region was a minor earthquake of magnitude 3.2 9 miles SE of Mammoth Lakes, CA at 02:55 AM UTC Monday, May 03, 1999 (07:55 PM PDT Sunday, May 02, 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 APR 29 559 9.65 38 48.58 122 50.42 0.03 36 .27 .4 1.4 GEY # 2.5D 99 APR 29 703 43.23 36 32.59 121 7.90 5.55 54 1 .05 .1 .3 PIN 2.7D 99 APR 29 1447 5.81 38 49.54 122 48.17 2.09 33 .04 .1 .2 GEY 2.5D 99 APR 29 2034 24.66 36 34.34 121 9.94 3.07 47 1 .05 .1 .2 PIN 2.3D 99 APR 30 614 47.90 36 32.67 121 8.00 5.60 42 1 .04 .1 .4 PIN 2.1D 99 MAY 1 329 51.97 36 48.80 121 31.57 5.62 51 2 .09 .2 .3 SJB 2.1D 99 MAY 1 512 5.68 37 26.83 118 36.75 16.44 29 .06 .3 .7 RVL 2.3D 99 MAY 2 449 14.99 37 54.50 121 59.73 10.86 54 2 .09 .1 .2 CON 2.1D 99 MAY 2 511 52.07 37 11.11 118 37.23 17.84 28 1 .05 .4 .9 KAI 2.2D 99 MAY 2 541 47.59 40 42.98 124 12.91 9.84 14 .04 .4 .8 EUR 2.1D 99 MAY 2 559 45.25 38 0.15 123 30.76 0.15 73 1 .27 .9 1.2 PON # 3.1D 99 MAY 2 735 0.28 35 38.44 119 41.14 10.74 39 2 .16 .7 1.2 BAK 2.5D 99 MAY 2 815 26.35 40 17.39 121 22.98 6.47 13 .05 .6 1.1 ALM 2.8D 99 MAY 2 1051 27.99 38 49.37 122 47.78 5.17 37 .05 .1 .3 GEY 2.4D 99 MAY 2 1529 34.61 37 31.49 118 52.10 7.99 30 .05 .2 .6 MOR 2.0D 99 MAY 3 23 14.82 35 38.05 119 42.49 11.51 37 1 .16 .6 1.3 BAK 2.5D 99 MAY 3 213 23.47 35 46.27 120 18.58 3.86 31 4 .06 .2 .5 GOL 2.1D 99 MAY 3 255 51.36 37 32.99 118 51.84 8.53 30 .07 .3 .5 MOR 3.2D 99 MAY 3 1424 23.77 36 40.94 121 18.43 4.03 55 2 .05 .1 .3 STN 2.3D 99 MAY 4 257 38.22 35 55.39 120 28.21 5.64 38 4 .05 .2 .2 MID 2.3D 99 MAY 4 2130 23.15 38 48.60 122 48.83 4.94 30 .06 .2 .4 GEY 2.5D 99 MAY 4 2300 13.49 38 46.15 122 43.76 2.91 34 .09 .2 .4 GEY 2.9D 99 MAY 4 2343 49.44 37 31.76 118 49.13 5.24 27 .06 .3 .9 MOR # 2.7D 99 MAY 4 2359 11.75 37 33.29 118 48.20 8.27 29 .06 .3 .6 MOR 3.1D 99 MAY 5 237 44.21 37 33.25 118 48.22 8.12 29 .06 .3 .6 MOR 2.4D
