SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey July 24, 1997 Weekly Earthquake Report for Southern California ------------------------------------------------ July 17 - 23, 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 818-395-6327. For daily updates, call our Earthquake Information Hotline: 818-395-6977. -------------------------------- This week's Report covers the time period from midnight Thursday morning, July 17, Universal Time (ie. GMT), to midnight Wednesday night, July 23, Universal Time. In local time, the period of coverage is from 5 p.m., July 16, Pacific Daylight Time, to 5 p.m., July 23, Pacific Daylight Time. We detected 249 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 The week was a quiet one, seismically speaking. The largest event on the list was a M2.8 Landers aftershock early Tuesday morning. There was a Coalinga quake the same size, less than an hour earlier, which is described in the Northern California Report. The only quake this week that was reported felt was a much smaller M2.3 in Orange County just after noon on Saturday. 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 ------------------------------------------------------------- 7/16 7:24 pm 36 1.9 117 47.0 2.7 9 mi. E of Coso Junction 7/16 8:41 pm 33 59.7 118 39.4 2.0 3 mi. SSE of Malibu 7/17 2:51 am 33 52.8 118 27.1 2.7 2 mi. W of Manhattan Beach 7/17 10:34 am 33 11.1 115 34.9 2.0 3 mi. ENE of Obsidian Butte 7/17 10:34 am 33 11.1 115 35.3 2.1 " 7/17 10:39 am 33 11.3 115 35.0 2.1 " 7/17 3:18 pm 32 31.9 116 7.5 2.0 15 mi. SSW of Ocotillo 7/17 6:36 pm 35 46.3 117 39.1 2.1 10 mi. N of Ridgecrest 7/18 8:59 am 34 2.6 117 17.3 2.4 2 mi. W of Loma Linda 7/18 11:33 am 33 17.8 116 9.7 2.4 10 mi. N of Ocotillo Wells 7/18 6:02 pm 33 10.8 115 35.7 2.1 2 mi. ENE of Obsidian Butte 7/18 8:03 pm 35 2.8 116 59.3 2.4 11 mi. N of Barstow 7/19 12:17 pm 33 52.0 117 50.4 2.3 2 mi. SW of Yorba Linda FELT 7/20 6:27 am 35 26.8 118 18.8 2.1 15 mi. SSE of town of Lake Isabella 7/20 10:20 am 33 50.9 118 36.8 2.2 13 mi. SSE of Malibu 7/20 10:23 am 34 58.3 116 48.9 2.5 13 mi. ENE of Barstow 7/20 2:05 pm 35 59.9 118 51.0 2.2 11 mi. ESE of Porterville 7/20 2:14 pm 34 9.1 117 19.9 2.2 3 mi. NW of San Bernardino 7/20 8:34 pm 34 14.6 118 28.8 2.2 2 mi. SSE of Granada Hills 7/21 12:26 pm 32 21.2 115 10.1 2.7 28 mi. SE of Calexico 7/21 2:02 pm 34 9.1 117 20.3 2.1 3 mi. NNE of Rialto 7/22 1:42 am 32 46.1 115 32.9 2.2 1 mi. S of El Centro 7/22 3:41 am 36 3.8 117 38.5 2.6 17 mi. E of Coso Junction 7/22 4:21 am 36 17.6 120 24.4 2.8 11 mi. NNW of Coalinga 7/22 5:15 am 34 1.0 116 19.5 2.8 8 mi. S of Joshua Tree 7/23 4:40 am 34 9.4 117 20.3 2.1 3 mi. NNE of Rialto 7/23 5:18 am 34 2.2 117 33.3 2.5 5 mi. SSE of Rancho Cucamonga 7/23 5:30 am 33 44.3 117 7.5 2.1 3 mi. SSE of Perris 7/23 12:48 pm 36 5.5 117 39.5 2.0 16 mi. E of Coso Junction -------------------------------------------------------------