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 4.5 3 miles NNW of Redding, CA at 08:38 AM UTC Tuesday, Jul 21, 1998 (01:38 AM PDT Tuesday, Jul 21, 1998).
This earthquake was the largest recorded event observed in this region since the USGS began monitoring in the early 1980's. However, seismicity in this region is not unusual. On 940307 a M3.3 event occurred in the same location and depth, and since 1982 more than 160 quakes have been recorded with 10 km of this earthquake. The focal mechanism for this quake is unusual, indicating oblique reverse motion on a steeply dipping fault to the ESE, or oblique right-lateral motion on a shallow dipping fault to the north. Three M>2 aftershocks have been recorded so far.
The largest event to occur this week in this region was a minor earthquake of magnitude 3.0 5 miles NE of Gilroy, CA at 06:54 PM UTC Wednesday, Jul 22, 1998 (11:54 AM PDT Wednesday, Jul 22, 1998).
This earthquake occurred on the Calaveras fault.
The largest event to occur this week in this region was a minor earthquake of magnitude 3.5 8 miles WSW of Toms Place, CA at 12:42 AM UTC Saturday, Jul 18, 1998 (05:42 PM PDT Friday, Jul 17, 1998).
Seismic activity continues in the same vicinity as the M5.1 of 980714.
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 98 JUL 16 12 9.65 37 31.90 118 47.96 5.62 30 .05 .3 .7 MOR 2.3D 98 JUL 16 224 59.58 37 33.89 118 47.72 6.84 31 .06 .3 .6 MOR 3.0D 98 JUL 16 259 12.95 37 33.81 118 47.64 6.93 32 1 .05 .3 .6 MOR 3.5D 98 JUL 16 330 42.57 37 33.29 118 48.62 5.61 29 .07 .3 .6 MOR 2.3D 98 JUL 16 339 53.76 37 33.20 118 48.52 5.63 27 .07 .3 .6 MOR 2.5D 98 JUL 16 409 49.66 36 52.60 121 36.44 5.74 47 .10 .2 .3 SJB 2.3D 98 JUL 16 720 38.41 37 31.25 118 48.64 6.12 26 .07 .3 .8 MOR 2.4D 98 JUL 16 757 3.77 37 35.55 118 47.87 7.21 26 .07 .3 .6 MOR 2.3D 98 JUL 16 1121 59.90 37 32.57 118 48.40 5.62 27 .06 .3 .7 MOR 2.1D 98 JUL 16 1211 13.06 37 32.21 118 48.89 5.67 22 .05 .4 .8 MOR 2.2D 98 JUL 16 1220 11.72 37 38.68 118 54.58 7.68 24 .08 .3 .5 SMO 2.2D 98 JUL 16 1236 23.28 37 31.54 118 48.85 4.68 24 .06 .3 .8 MOR 2.3D 98 JUL 16 2019 40.85 37 31.24 118 49.42 3.96 32 1 .06 .2 .6 MOR 2.9D 98 JUL 16 2228 11.45 37 29.39 118 48.75 3.15 31 1 .06 .2 1.2 MOR 3.2D 98 JUL 16 2239 10.71 37 29.65 118 48.98 0.04 17 .13 .9 1.1 MOR # 2.4D 98 JUL 16 2258 5.77 36 39.98 121 17.26 3.06 55 1 .08 .1 .3 STN 2.3D 98 JUL 16 2319 37.12 37 29.18 118 48.70 2.92 30 .06 .2 1.3 MOR 2.8D 98 JUL 16 2329 48.78 37 32.66 118 49.79 1.20 8 .03 .3 .4 MOR 2.3D 98 JUL 17 55 34.32 37 34.99 118 49.74 4.35 32 1 .07 .3 .4 MOR 2.9D 98 JUL 17 527 12.73 36 39.51 121 16.51 3.22 43 .07 .1 .3 STN 2.4D 98 JUL 17 613 13.02 37 32.35 118 49.12 4.36 25 .07 .3 1.0 MOR 2.9D 98 JUL 17 614 36.41 37 32.47 118 49.74 1.09 27 .06 .2 .4 MOR 2.9D 98 JUL 17 636 32.92 37 32.50 118 48.83 4.49 30 .08 .3 .7 MOR 2.6D 98 JUL 17 833 7.03 38 47.95 122 47.30 0.68 20 .04 .2 .3 GEY 2.2D 98 JUL 17 924 19.57 37 31.62 118 49.67 3.71 33 2 .06 .2 .6 MOR 2.2D 98 JUL 17 957 43.48 37 32.56 118 47.33 6.12 28 .06 .3 .7 MOR 2.1D 98 JUL 17 1112 48.50 37 32.61 118 48.47 3.77 25 .09 .4 1.2 MOR 2.4D 98 JUL 17 1148 32.40 37 33.20 118 48.91 4.51 26 .06 .3 .7 MOR 2.8D 98 JUL 17 1315 57.37 37 31.31 118 48.89 3.72 22 .06 .4 .9 MOR 2.2D 98 JUL 17 1340 42.95 37 31.05 118 49.03 3.10 23 .05 .4 1.2 MOR 2.5D 98 JUL 17 1353 34.45 37 33.91 118 47.47 6.37 27 .06 .3 .6 MOR 2.3D 98 JUL 17 1438 30.22 37 33.16 118 49.66 0.00 16 .06 .5 .9 MOR # 2.2D 98 JUL 17 1454 41.53 37 32.84 118 49.64 1.54 14 .04 .3 .5 MOR 2.5D 98 JUL 17 1528 36.57 37 32.75 118 49.62 1.29 21 .07 .2 .5 MOR 2.2D 98 JUL 17 1546 0.75 37 32.27 118 48.34 5.37 28 .07 .3 .8 MOR 2.7D 98 JUL 17 1652 4.41 37 34.20 118 47.60 4.61 31 1 .08 .3 .6 MOR 3.0D 98 JUL 17 1729 42.13 37 35.61 118 49.60 6.01 30 .07 .2 .4 MOR 2.6D 98 JUL 17 2007 37.92 37 34.06 118 47.58 4.66 29 .06 .2 .6 MOR 2.8D 98 JUL 17 2103 25.67 37 32.74 118 47.58 6.22 30 .06 .2 .6 MOR 3.0D 98 JUL 17 2120 31.31 37 29.51 118 42.11 6.52 15 .18 1.1 3.9 WCN 2.3D 98 JUL 17 2329 59.12 37 32.91 118 49.63 3.05 19 .06 .6 1.3 MOR 2.2D 98 JUL 18 29 48.80 37 31.54 118 49.08 3.58 18 .06 .8 1.4 MOR 2.2D 98 JUL 18 37 57.43 37 31.31 118 49.07 3.37 19 .06 .7 1.7 MOR 2.3D 98 JUL 18 42 42.13 37 31.30 118 49.34 3.94 31 .07 .3 .9 MOR 3.5D 98 JUL 18 221 1.95 37 32.20 118 49.22 3.40 28 .07 .3 1.4 MOR 2.8D --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 98 JUL 18 420 29.15 37 32.56 118 47.44 6.05 25 .06 .3 .7 MOR 2.2D 98 JUL 18 439 39.33 37 33.34 118 48.50 5.95 31 .06 .3 .5 MOR 2.4D 98 JUL 18 525 53.64 37 33.32 118 48.42 5.79 27 .07 .3 .6 MOR 2.2D 98 JUL 18 542 48.21 37 33.43 118 47.26 3.19 25 .06 .3 1.1 MOR 2.0D 98 JUL 18 635 14.81 37 41.48 121 37.39 17.38 43 .14 .3 .4 HAM 2.4D 98 JUL 18 731 54.55 37 31.76 118 48.00 5.42 21 .06 .4 .9 MOR 2.2D 98 JUL 18 816 39.74 37 34.28 118 48.00 6.67 26 .07 .3 .6 MOR 2.4D 98 JUL 18 1304 42.88 37 33.89 118 47.95 6.76 26 .06 .3 .8 MOR 2.2D 98 JUL 18 1448 57.40 37 33.02 118 48.99 4.93 27 .06 .2 .5 MOR 2.5D 98 JUL 18 1520 41.70 37 34.01 118 47.90 6.87 28 .06 .3 .6 MOR 2.3D 98 JUL 18 1522 13.09 37 29.67 118 49.19 2.54 27 .05 .3 2.1 MOR 2.5D 98 JUL 18 1924 21.06 37 33.03 118 48.44 5.37 22 .04 .4 .6 MOR 2.3D 98 JUL 19 404 27.29 37 33.52 118 48.48 5.35 25 .06 .4 .6 MOR 2.0D 98 JUL 19 652 5.28 38 44.66 122 42.84 0.03 23 .36 .6 1.7 NAP # 2.2D 98 JUL 19 1034 23.94 37 33.99 118 47.35 7.37 30 .07 .3 .6 MOR 3.4D 98 JUL 19 1533 30.90 37 32.31 118 48.73 5.12 29 .05 .3 .6 MOR 2.3D 98 JUL 20 19 27.46 37 32.06 118 48.80 5.82 26 .04 .2 .5 MOR 2.3D 98 JUL 20 451 8.49 37 32.76 118 48.72 5.20 32 1 .06 .2 .6 MOR 3.2D 98 JUL 20 508 1.64 37 33.30 118 48.47 5.36 24 .05 .4 .6 MOR 2.2D 98 JUL 20 515 42.26 37 33.26 118 48.45 5.46 22 .05 .4 .6 MOR 2.1D 98 JUL 20 638 49.85 40 16.75 122 22.89 34.02 11 .03 .4 .9 KLA 2.1D 98 JUL 20 715 48.86 37 35.96 118 49.09 6.71 26 .07 .3 .5 MOR 2.4D 98 JUL 20 850 53.73 38 45.96 122 41.56 4.07 26 .07 .2 .5 GEY 2.4D 98 JUL 20 1905 27.60 41 19.97 122 9.32 10.28 12 2 .03 .4 .6 SHA 2.1D 98 JUL 21 234 58.03 37 31.97 118 49.01 5.35 30 .06 .2 .6 MOR 2.1D 98 JUL 21 838 49.88 40 37.48 122 24.30 23.03 32 1 .27 .4 1.0 SHA 4.5L 98 JUL 21 1037 56.22 40 37.07 122 22.21 19.72 12 .06 .5 .9 SHA 2.2D 98 JUL 21 1103 15.42 37 33.83 118 47.40 7.55 31 .06 .3 .6 MOR 2.1D 98 JUL 21 1142 39.43 40 36.68 122 21.97 19.00 11 1 .07 .6 .9 SHA 2.2D 98 JUL 21 1551 52.35 40 37.02 122 22.12 19.10 12 .07 .5 .7 SHA 2.1D 98 JUL 21 2104 37.16 37 28.95 118 50.09 3.43 19 .05 .3 1.0 MOR 2.3D 98 JUL 21 2208 1.03 37 33.44 118 50.02 3.37 29 .07 .2 .6 MOR 2.5D 98 JUL 22 15 45.78 37 20.20 121 42.13 8.27 80 5 .04 .1 .2 ALU 2.6D 98 JUL 22 500 42.15 37 34.17 118 47.58 7.14 28 .07 .3 .6 MOR 2.4D 98 JUL 22 645 4.94 37 35.47 118 48.09 5.68 27 .05 .3 .5 MOR 2.4D 98 JUL 22 741 14.78 37 32.80 118 49.68 0.73 25 .05 .3 .7 MOR 2.8D 98 JUL 22 1140 43.56 38 47.84 122 46.77 5.33 41 .07 .2 .3 GEY 3.0D 98 JUL 22 1658 2.85 38 49.46 122 48.21 4.57 19 .04 .2 .4 GEY 2.1D 98 JUL 22 1853 8.64 37 3.49 121 29.68 4.46 64 .06 .1 .3 CYS 2.4D 98 JUL 22 1854 19.17 37 3.55 121 29.72 4.47 65 .07 .2 .3 CYS 3.0D
