SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey May 16, 1996 Weekly Earthquake Report for Southern California ------------------------------------------------ May 9 - 15, 1996 Prepared by: Debbie Wells, 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 818-395-6326. For daily updates, call our Earthquake Information Hotline: 818-395-6977. -------------------------------- This week's Report covers the time period from midnight Thursday morning, May 9, Universal Time (ie. GMT), to midnight Wednesday night, May 15, Universal Time. In local time, the period of coverage is from 5 p.m., May 8, Pacific Daylight Time, to 5 p.m., May 15, Pacific Daylight Time. We detected and processed 305 earthquakes during the 7-day period covered. This week's activity included a M3.0 or greater for each of our current sequences. A M3.0 in the Barstow area on Sunday morning was an aftershock of the Landers earthquake (Mw7.3, June 28, 1992). It was not felt. Surprisingly, the M3.5 near Ridge- crest on Sunday evening also was not reported felt. We assume that it was felt by some, who simply decided it wasn't worth calling about. This was an aftershock of the M5.8 Ridgecrest earthquake (September 20, 1995). The Northridge sequence (main- shock Mw6.7, January 17, 1994) checked in with a M3.0 aftershock on Wednesday afternoon, near San Fernando, that was felt. The only other quake that was felt was a M3.0 north of Borrego Springs on Thursday afternoon. This was in the San Jacinto Fault Zone, a regular producer of small quakes. The table 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 ------------------------------------------------------------- 5/9 2:53 am 35 54.5 119 40.8 2.1 36 mi. SW of Visalia 5/9 7:39 am 34 56.7 116 52.9 2.8 8 mi. ENE of Barstow 5/9 11:01 am 34 9.1 116 25.4 2.4 2 mi. NNE of Yucca Valley 5/9 11:42 am 33 50.2 118 7.1 2.3 1 mi. SSE of Lakewood 5/9 12:10 pm 33 27.3 116 25.4 3.0 14 mi. NNW of Borrego Springs; FELT 5/9 6:52 pm 32 18.1 115 8.1 2.0 32 mi. SE of Calexico 5/9 7:35 pm 35 1.8 118 59.1 2.0 2 mi. NW of Wheeler Ridge 5/9 8:43 pm 33 49.6 118 7.1 2.0 2 mi. S of Lakewood 5/10 7:40 am 33 54.4 119 45.6 2.3 14 mi. SE of Santa Cruz Is. (NW end) 5/11 5:45 am 34 0.8 116 18.7 2.4 8 mi. S of Joshua Tree 5/11 9:14 am 33 0.7 117 49.2 2.5 30 mi. SSW of San Clemente 5/11 11:09 pm 35 46.7 116 38.6 2.2 24 mi. WSW of Shoshone 5/12 3:22 am 33 21.2 116 26.2 2.1 7 mi. NNW of Borrego Springs 5/12 10:29 am 34 58.1 116 49.0 3.0 12 mi. ENE of Barstow 5/12 12:55 pm 34 7.0 116 58.7 2.2 6 mi. NNE of Yucaipa 5/12 8:32 pm 35 44.2 117 37.5 2.4 8 mi. NNE of Ridgecrest 5/12 8:33 pm 35 44.1 117 37.6 3.5 " 5/12 9:41 pm 35 44.2 117 37.7 2.0 " 5/13 6:47 am 34 1.2 116 19.0 2.5 8 mi. S of Joshua Tree 5/13 6:48 am 34 1.3 116 18.9 2.1 7 mi. S of Joshua Tree 5/13 5:23 pm 33 49.8 118 7.5 2.0 2 mi. S of Lakewood 5/14 2:24 am 35 57.3 117 42.5 2.4 14 mi. ESE of Coso Junction 5/14 3:47 am 33 55.1 118 36.0 2.6 9 mi. SSE of Malibu 5/14 5:55 am 35 44.1 117 37.2 2.2 8 mi. NNE of Ridgecrest 5/14 7:46 am 34 2.3 118 3.2 2.1 Under Whittier Narrows 5/14 8:56 am 34 28.8 116 30.5 2.3 25 mi. N of Yucca Valley 5/14 1:30 pm 34 16.3 116 24.5 2.4 10 mi. N of Yucca Valley 5/14 7:37 pm 33 10.9 115 35.9 2.0 2 mi. ENE of Obsidian Butte 5/14 7:38 pm 33 11.0 115 36.3 2.4 " 5/14 7:44 pm 33 42.2 116 45.5 2.3 3 mi. SW of Idyllwild 5/15 5:14 am 34 14.6 118 31.9 2.2 Under Northridge 5/15 5:45 am 33 52.7 116 9.2 2.1 11 mi. NNE of Indio 5/15 12:43 pm 34 7.0 119 11.0 2.1 2 mi. SSE of Port Hueneme 5/15 3:16 pm 34 16.4 118 27.8 3.0 1 mi. WSW of Pacoima; FELT -------------------------------------------------------------