SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey December 18, 1997 Weekly Earthquake Report for Southern California ------------------------------------------------ December 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. -------------------------------- ****************************************************************** As many of you know by now, the U.S. Geological Survey in Menlo Park, the office which originates the Northern California Earthquake Report, is planning to discontinue the paper (and faxed) Report at the end of January 1998. We plan to follow their initiative. As of the beginning of February 1998, we will be replacing our weekly 'treeware' product with a Web site, which will include the same map, table, and commentary as the current Weekly Report, plus other features. The Web page will be updated more often than once per week. There will be no paper copy or usenet distribution. We hope we are giving our Users sufficient notice to obtain World Wide Web access for themselves. At minimum, most public libraries now provide Web access, along with the capability to print copies of Web pages. ****************************************************************** This week's Report covers the time period from midnight Thursday morning, December 11 Universal Time (ie. UTC), to midnight Wednesday night, December 17, Universal Time. In local time, the period of coverage is from 4 p.m., December 10, Pacific Standard Time, to 4 p.m., December 17, Pacific Standard Time. We detected 193 earthquakes during the seven-day period covered. Because next week, a Holiday falls in the middle of the week, we are planning to skip a Weekly Report. A Report will be produced on December 31 covering almost two weeks. After that, the Report will be on schedule through the end of January. 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 This week was another one of those quiet weeks. There were no earthquakes reported felt and, aside from one near Coalinga which is covered in the Menlo Park's Report, there were none above M3. The largest was a M2.9 near Hemet on Friday. 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 ------------------------------------------------------------- 12/10 6:38 pm 32 28.3 115 22.8 2.3 15 mi. SSE of Calexico 12/10 9:06 pm 36 7.4 117 41.2 2.7 15 mi. ENE of Coso Junction 12/11 1:27 am 33 10.8 116 2.7 2.2 5 mi. ENE of Ocotillo Wells 12/11 5:20 am 34 0.5 116 43.4 2.2 6 mi. NNE of Cabazon 12/11 12:45 pm 36 1.5 118 16.4 2.1 18 mi. W of Coso Junction 12/12 3:36 am 36 6.7 120 13.0 3.4 8 mi. ESE of Coalinga 12/12 6:08 am 33 34.9 116 56.6 2.9 11 mi. S of Hemet 12/12 9:39 am 33 11.1 116 2.6 2.0 5 mi. ENE of Ocotillo Wells 12/12 5:08 pm 32 57.9 115 33.1 2.3 Under Brawley 12/13 10:09 pm 35 41.9 118 24.5 2.2 5 mi. NE of town of Lake Isabella 12/13 11:13 pm 32 40.5 115 40.8 2.8 11 mi. SW of El Centro 12/13 11:29 pm 32 40.0 115 40.5 2.1 " 12/14 9:21 am 34 58.3 116 48.1 2.0 13 mi. ENE of Barstow 12/15 3:00 am 36 59.6 118 13.0 2.2 13 mi. N of Independence 12/15 3:10 am 33 13.2 115 40.9 2.0 4 mi. NW of Obsidian Butte 12/15 7:50 pm 36 12.6 117 51.6 2.6 9 mi. ESE of Olancha 12/16 7:28 am 33 57.2 117 5.0 2.4 6 mi. SSW of Yucaipa 12/16 2:42 pm 34 37.2 116 39.8 2.3 20 mi. NE of Lucerne Valley 12/16 9:53 pm 33 15.9 116 2.1 2.1 4 mi. WSW of Salton City 12/17 12:11 pm 36 1.6 117 36.2 2.3 19 mi. E of Coso Junction 12/17 12:41 pm 33 24.8 116 28.1 2.1 12 mi. NNW of Borrego Springs 12/17 3:34 pm 36 8.0 117 40.9 2.5 16 mi. ENE of Coso Junction -------------------------------------------------------------