SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey September 18, 1997 Weekly Earthquake Report for Southern California ------------------------------------------------ September 11 - 17, 1997 Prepared by: Kate Hutton, Seismological Laboratory (kate@bombay.gps.caltech.edu) Lucy Jones, U. S. Geological Survey California Institute of Technology For further information, please contact the authors, or the Caltech Public Relations Office at 626-395-6327. For daily updates, call our Earthquake Information Hotline: 626-395-6977. -------------------------------- ***************************************************************** If you receive this Report by FAX and if you have recently had a change of AREA CODE, please notify us ASAP. We have no other way to know which fax numbers need to be changed!! ***************************************************************** This week's Report covers the time period from midnight Thursday morning, September 11, Universal Time (ie. UTC), to midnight Wednesday night, September 17, Universal Time. In local time, the period of coverage is from 5 p.m., September 10, Pacific Daylight Time, to 5 p.m., September 17, Pacific Daylight Time. We detected 280 earthquakes during the seven-day period covered. These Weekly Reports should not be used for archival purposes. Further data processing often changes the magnitudes slightly and, especially during times of high seismicity, sometimes changes the estimates of total seismicity. For the best earthquake catalog currently available, see: http://scec.gps.caltech.edu/catalog-search.html With the exception of the continuing swarm activity in northern Mexico, this was a very quiet week. There were no events reported felt for the entire week. Our largest event was a M3.4 in the Fillmore region very early Sunday morning. This event was too far west to be considered a Northridge aftershock. As usual for that area, however, the focal mechanism was thrust. There were also a M3.1 on Friday morning in southwestern Nevada, and a M3.2 in the Coalinga area the same morning. The reader is referred to the Northern California Earthquake Report for further information on the latter event. Table 1 lists the quakes this week that were M2.0 or larger in the central part of the coverage area. Times are local times; if you want Greenwich Mean Time, add 7 hrs to the Pacific Daylight Time or 8 hrs to the Pacific Standard Time listed. Table 1 ------- Date Time N Lat. W Long. Mag ------------------------------------------------------------- 9/11 11:31 am 33 19.0 116 20.0 2.2 4 mi. NNE of Borrego Springs 9/11 1:52 pm 32 39.3 115 54.1 2.0 7 mi. SE of Ocotillo 9/11 8:05 pm 34 19.2 118 45.8 2.0 4 mi. NW of Simi Valley 9/11 11:16 pm 34 2.3 116 19.4 2.2 6 mi. S of Joshua Tree 9/12 5:29 am 36 7.3 120 29.5 2.6 7 mi. W of Coalinga 9/12 6:36 am 36 53.2 116 16.6 3.1 43 mi. NE of Furnace Creek 9/12 9:20 am 36 1.6 117 45.9 2.7 10 mi. E of Coso Junction 9/12 9:20 am 36 15.1 120 16.7 3.2 9 mi. NNE of Coalinga 9/12 10:03 am 34 48.4 120 55.1 2.4 15 mi. WSW of Pt. Sal 9/12 1:18 pm 34 37.2 116 40.7 2.0 19 mi. NE of Lucerne Valley 9/12 1:57 pm 32 11.2 115 45.3 2.7 36 mi. SSW of Calexico 9/12 4:47 pm 34 9.8 120 30.4 2.4 12 mi. NW of San Miguel Is. 9/12 4:55 pm 32 8.9 115 46.6 2.6 39 mi. SSW of Calexico 9/12 9:20 pm 32 41.0 115 42.2 2.2 11 mi. SW of El Centro 9/13 2:14 am 33 17.2 119 16.4 2.2 13 mi. ENE of San Nicolas Is. 9/13 1:28 pm 36 2.0 117 46.4 2.2 9 mi. E of Coso Junction 9/13 8:02 pm 35 13.2 117 14.4 2.3 21 mi. WSW of Goldstone Lake 9/14 1:31 am 34 27.5 119 0.6 3.4 6 mi. NW of Fillmore 9/14 7:10 am 36 6.8 117 39.2 2.0 17 mi. ENE of Coso Junction 9/14 10:45 am 34 21.6 116 27.5 2.1 16 mi. N of Yucca Valley 9/14 7:13 pm 32 42.0 115 24.4 2.7 5 mi. ENE of Calexico 9/14 7:54 pm 36 0.6 117 48.4 2.4 8 mi. ESE of Coso Junction 9/14 9:23 pm 34 9.3 116 26.3 2.1 2 mi. N of Yucca Valley 9/15 3:55 am 36 6.3 117 39.7 2.1 16 mi. ENE of Coso Junction 9/15 6:50 am 32 31.6 115 16.7 2.5 15 mi. SE of Calexico 9/15 8:09 am 33 10.1 115 40.2 2.1 1 mi. W of Obsidian Butte 9/15 10:02 am 33 10.1 115 39.8 2.0 " 9/15 10:10 am 33 9.6 115 38.9 2.6 " 9/15 2:39 pm 35 10.5 117 15.2 2.4 23 mi. NNW of Barstow 9/15 8:38 pm 33 21.7 116 18.4 2.1 8 mi. NNE of Borrego Springs 9/15 9:43 pm 35 47.3 117 40.3 2.0 11 mi. N of Ridgecrest 9/16 2:05 am 32 16.3 115 7.9 2.7 34 mi. SE of Calexico 9/16 2:38 am 33 55.6 120 15.9 2.3 9 mi. SE of San Miguel Is. 9/16 3:03 am 32 16.5 115 8.2 3.0 34 mi. SE of Calexico 9/16 3:21 am 32 17.4 115 8.4 2.8 " 9/16 8:13 am 32 17.8 115 8.3 2.5 " 9/16 8:59 am 32 18.1 115 7.4 2.8 " 9/16 8:14 pm 35 1.6 116 58.3 2.2 10 mi. NNE of Barstow 9/16 8:41 pm 33 13.6 116 14.2 2.1 8 mi. NW of Ocotillo Wells 9/16 9:36 pm 34 15.9 119 36.3 2.0 10 mi. SSW of Carpinteria 9/16 9:56 pm 36 53.0 116 5.8 2.4 51 mi. NE of Furnace Creek 9/17 1:08 am 32 17.6 115 8.7 2.9 32 mi. SE of Calexico 9/17 8:13 am 32 39.6 115 54.2 2.4 7 mi. SE of Ocotillo 9/17 8:18 am 33 38.5 117 57.4 2.5 2 mi. NW of Newport Beach 9/17 10:44 am 32 13.3 115 48.0 2.5 35 mi. SSW of Calexico 9/17 1:16 pm 32 32.2 115 38.2 2.3 12 mi. SW of Calexico 9/17 2:03 pm 34 21.8 118 44.3 2.7 6 mi. NNW of Simi Valley 9/17 3:16 pm 32 31.7 115 37.7 2.5 12 mi. SW of Calexico 9/17 3:16 pm 32 34.8 115 38.8 3.3 10 mi. SW of Calexico -------------------------------------------------------------