SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey March 5, 1998 Weekly Earthquake Report for Southern California ------------------------------------------------ February 26 - March 4, 1998 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, has discontinued their Weekly Report. We plan to follow their initiative. As of late March 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. You will be able to get to this web site form the following home pages: http://www.gps.caltech.edu/seismo/ http://www-socal.wr.usgs.gov/ http://www.scecdc.scec.org/ http://www.trinet.org/ (The last one does not exist yet, but will soon.) 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, February 26, Universal Time (ie. UTC), to midnight Wednesday night, March 4, Universal Time. In local time, the period of coverage is from 4 p.m., February 25, Pacific Standard Time, to 4 p.m., March 4, Pacific Standard Time. We detected 198 earthquakes during the seven-day period covered. We had another quiet week. The largest events inside our coverage area were both M2.8's. The first was an Northridge aftershock, near Simi Valley on Sunday. The other one was a Landers aftershock on Tuesday afternoon. Neither generated any public interest. The focal mechanisms were the usual for those areas: thrust for the Northridge quake and strike-slip for the Landers. 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 ------------------------------------------------------------- 2/25 8:12 pm 35 54.0 117 55.0 2.2 10 mi. S of Coso Junction 2/25 10:19 pm 33 45.2 118 0.7 2.4 3 mi. WSW of Garden Grove 2/26 11:33 pm 36 23.6 120 54.5 2.9 35 mi. WNW of Coalinga 2/27 2:01 pm 33 39.3 117 3.8 2.0 8 mi. SW of Hemet 2/27 4:47 pm 32 0.4 115 45.8 3.0 48 mi. SSW of Calexico 2/27 9:53 pm 35 50.5 117 42.8 2.1 15 mi. N of Ridgecrest 2/27 8:16 pm 33 13.8 115 57.4 2.2 3 mi. S of Salton City 2/27 8:24 pm 33 52.3 120 7.1 2.1 5 mi. S of Santa Rosa Is. 3/1 6:09 am 33 13.9 115 57.8 2.0 3 mi. S of Salton City 3/1 8:12 am 34 0.5 119 4.3 2.3 8 mi. WSW of Leo Carrillo State Beach 3/1 7:27 pm 35 47.5 117 38.7 2.2 11 mi. N of Ridgecrest 3/1 7:27 pm 34 14.4 118 40.6 2.8 3 mi. SE of Simi Valley 3/1 11:30 pm 36 1.5 117 52.4 2.1 4 mi. ESE of Coso Junction 3/2 11:44 am 36 1.4 117 52.5 2.4 " 3/2 1:31 pm 32 23.2 115 18.6 2.1 22 mi. SSE of Calexico 3/2 2:46 pm 32 51.4 117 36.0 2.3 20 mi. W of La Jolla 3/2 7:27 pm 36 4.6 117 50.3 2.2 6 mi. ENE of Coso Junction 3/2 8:21 pm 36 4.5 117 50.3 2.3 " 3/2 8:38 pm 36 4.5 117 50.3 2.2 " 3/2 9:06 pm 35 18.2 118 29.8 2.3 12 mi. NNW of Tehachapi 3/3 12:50 am 36 14.2 118 6.3 2.0 6 mi. WSW of Olancha 3/3 1:40 am 34 15.4 118 33.6 2.2 2 mi. NW of Northridge 3/3 6:19 am 32 35.7 117 58.5 2.3 26 mi. SE of San Clemente Is. (SE tip) 3/3 12:59 pm 34 25.1 116 28.7 2.8 20 mi. N of Yucca Valley 3/4 12:26 am 36 14.9 118 17.9 2.3 16 mi. W of Olancha 3/4 2:10 pm 34 18.5 116 26.7 2.2 13 mi. N of Yucca Valley -------------------------------------------------------------