SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey February 26, 1998 Weekly Earthquake Report for Southern California ------------------------------------------------ February 19 - 25, 1998 Prepared by: Nick Scheckel, 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 February 1998. We plan to follow their initiative. As of the beginning of 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 19, Universal Time (ie. UTC), to midnight Wednesday night, February 25, Universal Time. In local time, the period of coverage is from 4 p.m., February 18, Pacific Standard Time, to 4 p.m., February 25, Pacific Standard Time. We detected 169 earthquakes during the seven-day period covered. Note that we have decided to extend the production of the Weekly Report through February, or until we have thoroughly tested some of our newest software. We had even a quieter week than last, though we had at least one earthquake over a M3.0. It was a M3.4 off the southeast tip of San Clemente Island on Saturday morning. Also, there was another "small" earthquake (defined as being less than magnitude 5) in Mexico. It was a M4.8 early Tuesday morning and was located further south than than last week's M4.9. Its location was 112 mi. S of the Imperial Valley town of El Centro, last week's was 68 mi. S of El Centro. The location is off the southern edge of our Weekly Report map. 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 ------------------------------------------------------------- 2/19 2:55 pm 35 41.9 116 34.0 2.3 25 mi. SW of Shoshone 2/19 6:31 pm 32 58.5 117 46.9 2.2 27 mi. WSW of Oceanside 2/20 8:47 am 32 9.6 115 44.9 2.5 38 mi. SSW of Calexico 2/20 11:25 am 32 11.1 115 46.5 2.8 37 mi. SSW of Calexico 2/20 12:15 pm 32 5.3 115 53.6 2.2 45 mi. S of Ocotillo 2/20 7:55 pm 34 38.3 116 30.2 2.0 28 mi. ENE of Lucerne Valley 2/20 8:40 pm 35 49.2 117 42.3 2.5 13 mi. N of Ridgecrest 2/20 8:47 pm 35 49.1 117 42.1 2.2 13 mi. N of Ridgecrest 2/21 1:19 am 32 33.4 115 18.1 2.5 13 mi. SE of Calexico 2/21 4:23 am 35 47.2 117 38.7 2.2 11 mi. N of Ridgecrest 2/21 9:39 am 32 43.9 118 4.6 3.4 16 mi. ESE of San Clemente Is. (SE tip) 2/21 11:04 pm 33 11.4 115 34.0 2.0 4 mi. SW of Niland 2/22 1:08 am 32 15.1 115 49.4 2.0 34 mi. SSE of Ocotillo 2/22 2:51 am 33 46.6 116 11.5 2.0 4 mi. NNE of Indio 2/22 6:47 am 35 46.4 118 18.7 2.2 12 mi. NE of town of Lake Isabella 2/22 9:32 pm 34 22.4 118 39.5 2.0 5 mi. WSW of Valencia 2/23 12:43 am 35 47.2 117 38.7 2.5 11 mi. N of Ridgecrest 2/23 10:50 am 35 5.8 118 18.6 2.3 8 mi. ESE of Tehachapi 2/23 4:08 pm 33 12.1 116 21.2 2.0 3 mi. SSE of Borrego Springs 2/23 4:41 pm 36 32.9 118 5.6 2.4 4 mi. SSW of Lone Pine 2/23 10:59 pm 34 22.8 116 28.1 2.3 18 mi. N of Yucca Valley 2/24 7:47 am 34 22.8 116 28.5 2.0 18 mi. N of Yucca Valley 2/25 6:07 am 34 5.9 117 0.3 2.3 4 mi. NNE of Yucaipa 2/25 8:08 am 36 32.7 118 5.3 2.1 4 mi. SSW of Lone Pine 2/25 12:18 pm 32 38.6 117 18.5 2.0 9 mi. SSW of Mission Beach -------------------------------------------------------------