SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey March 19, 1998 Weekly Earthquake Report for Southern California ------------------------------------------------ March 12 - 18, 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. Commentary on current notable quakes can be found on http://www.trinet.org/ and our day-to-day commentary will soon be there as well. After March 26, there will be no paper copy or usenet distribution. We hope we have 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, March 12, Universal Time (ie. UTC), to midnight Wednesday night, March 18, Universal Time. In local time, the period of coverage is from 4 p.m., March 11, Pacific Standard Time, to 4 p.m., March 18, Pacific Standard Time. We processed 409 earthquakes for the seven-day period covered. Most of this week's activity, including the largest event (ML3.8 on Wednesday), was part of the Coso Range sequence that started with a ML5.2 last week. This week's M3+ events, of which there were two, both have strike-slip focal mechanisms, consistent with the rest of the sequence. Two other M3+ quakes occurred, also both strike-slip, as it turns out. The first occured just north of Cabazon, which is in the San Gorgonio Pass, on Friday afternoon and had a magnitude of ML3.1. It was not at the same location as last week's Crafton Hills quake, and was unrelated to that quake. The second (ML3.0) occurred in the Anza-Borrego Desert very early on Monday morning. Neither of these two events attracted any public attention. 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 ------------------------------------------------------------- 3/11 5:14 pm 36 4.5 117 36.8 2.0 18 mi. E of Coso Junction 3/11 7:18 pm 36 4.4 117 37.9 2.1 17 mi. E of Coso Junction 3/11 7:53 pm 34 1.1 117 13.6 2.2 2 mi. SE of Loma Linda 3/12 12:11 am 36 3.7 117 38.3 2.1 17 mi. E of Coso Junction 3/12 4:26 am 33 51.7 118 39.9 2.1 12 mi. S of Malibu 3/12 5:21 am 36 5.0 117 39.3 2.2 16 mi. E of Coso Junction 3/12 8:08 am 32 57.3 117 37.3 2.0 21 mi. SW of Oceanside 3/12 9:05 am 36 4.3 117 37.5 2.0 18 mi. E of Coso Junction 3/12 9:33 am 36 4.2 117 37.3 2.5 " 3/12 12:32 pm 34 7.1 116 43.7 2.4 5 mi. ENE of Mt. San Gorgonio 3/12 1:36 pm 36 4.3 117 37.4 2.0 18 mi. E of Coso Junction 3/12 4:23 pm 36 4.5 117 37.0 2.4 " 3/12 5:28 pm 36 4.7 117 37.0 2.5 " 3/12 7:31 pm 36 5.5 117 39.8 2.3 16 mi. ENE of Coso Junction 3/12 8:21 pm 36 4.6 117 37.0 2.1 18 mi. E of Coso Junction 3/12 10:56 pm 36 4.8 117 39.2 2.1 16 mi. E of Coso Junction 3/13 1:32 am 33 18.0 116 11.7 2.2 11 mi. NNW of Ocotillo Wells 3/13 9:05 am 32 43.8 117 21.0 2.4 6 mi. WSW of Mission Beach 3/13 12:31 pm 36 4.4 117 37.0 2.4 18 mi. E of Coso Junction 3/13 1:08 pm 34 0.9 116 46.8 3.1 6 mi. N of Cabazon 3/13 5:24 pm 35 53.8 118 23.9 2.4 18 mi. NNE of town of Lake Isabella 3/13 8:48 pm 36 4.3 117 37.7 2.0 17 mi. E of Coso Junction 3/13 8:53 pm 36 4.6 117 37.3 2.1 18 mi. E of Coso Junction 3/13 10:08 pm 36 4.8 117 37.5 2.0 " 3/13 10:26 pm 33 51.3 118 30.6 2.1 6 mi. WSW of Manhattan Beach 3/13 11:16 pm 36 4.3 117 37.2 2.6 18 mi. E of Coso Junction 3/14 2:33 am 33 27.9 116 31.6 2.1 10 mi. SE of Anza 3/14 5:48 am 35 4.1 118 27.3 2.0 4 mi. S of Tehachapi 3/14 9:54 pm 36 4.7 117 36.9 2.0 18 mi. E of Coso Junction 3/15 8:59 am 36 5.3 117 37.6 2.0 " 3/15 9:12 am 36 5.4 117 37.5 2.0 " 3/15 3:39 pm 36 3.9 117 38.0 2.6 17 mi. E of Coso Junction 3/15 5:46 pm 36 8.8 120 1.5 2.3 18 mi. E of Coalinga 3/15 7:34 pm 36 4.1 117 37.2 2.6 18 mi. E of Coso Junction 3/15 8:19 pm 34 22.8 118 38.9 2.6 4 mi. WSW of Valencia 3/15 11:07 pm 33 43.5 118 0.2 2.1 3 mi. NE of Bolsa Chica Beach 3/15 11:19 pm 36 4.1 117 37.2 2.5 18 mi. E of Coso Junction 3/16 12:59 am 36 4.2 117 38.0 2.0 17 mi. E of Coso Junction 3/16 1:14 am 33 26.1 116 25.3 3.0 12 mi. NNW of Borrego Springs 3/16 3:50 am 35 43.2 117 39.1 2.5 6 mi. N of Ridgecrest 3/16 5:58 am 34 9.4 116 25.5 2.2 2 mi. NNE of Yucca Valley 3/16 8:03 am 34 2.5 116 19.1 2.2 6 mi. S of Joshua Tree 3/16 9:17 am 34 36.7 116 38.1 2.1 21 mi. ENE of Lucerne Valley 3/16 1:32 pm 36 4.2 117 37.7 2.0 17 mi. E of Coso Junction 3/17 2:17 am 33 12.2 115 34.9 2.0 3 mi. NE of Obsidian Butte 3/17 7:45 am 34 59.4 116 57.3 2.4 8 mi. NNE of Barstow 3/18 12:09 am 34 20.8 116 28.3 2.1 15 mi. N of Yucca Valley 3/18 12:39 am 33 36.3 117 17.0 2.4 5 mi. SSE of Lake Elsinore 3/18 1:42 am 36 4.3 117 37.4 2.2 18 mi. E of Coso Junction 3/18 6:18 am 36 5.3 117 37.8 2.1 " 3/18 10:13 am 36 4.8 117 36.9 3.1 " 3/18 12:06 pm 36 4.5 117 37.2 3.8 " 3/18 12:08 pm 36 4.4 117 37.4 2.6 " 3/18 12:10 pm 36 4.4 117 37.5 2.3 " 3/18 12:11 pm 36 4.6 117 37.5 2.7 " 3/18 1:14 pm 36 4.6 117 37.4 2.3 " -------------------------------------------------------------