SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey May 30, 1996 Weekly Earthquake Report for Southern California ------------------------------------------------ May 23 - 29, 1996 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 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 23, Universal Time (ie. GMT), to midnight Wednesday night, May 29, Universal Time. In local time, the period of coverage is from 5 p.m., May 22, Pacific Daylight Time, to 5 p.m., May 29, Pacific Daylight Time. We detected and processed 269 earthquakes during the 7-day period covered. The biggest excitement we had this week was the widely felt M3.5 earthquake which occurred on Thursday morning near downtown Los Angeles. This earthquake was caused by movement on a west striking thrust fault. It was located close to the 1981 M4.4 and M4.1 Montebello earthquakes. It is not possible to assign such a small earthquake to a specific fault, although the movement in the earthquake is consistent with ongoing north-south compression of the Los Angeles basin. A M3.5 occurs every year somewhere within the Los Angeles basin and thus this earthquake was simply a part of the background earthquake activity. The swarm which started last week in the Brawley Seismic Zone, at the south end of the Salton Sea, decreased greatly, producing only 4 earthquakes measuring M2.0 or greater this week. 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 ------------------------------------------------------------- 5/23 4:21 am 36 50.6 117 27.6 2.1 23 mi. NW of Stovepipe Wells 5/23 8:26 am 34 2.6 118 12.4 3.5 2 mi. WNW of East Los Angeles FELT 5/23 9:16 am 33 10.7 115 36.2 2.0 2 mi. ENE of Obsidian Butte 5/24 2:58 am 34 28.9 120 34.7 2.2 6 mi. W of Pt. Conception 5/24 10:18 am 33 8.5 115 38.4 2.2 1 mi. S of Obsidian Butte 5/24 4:54 pm 34 34.4 116 41.6 2.4 16 mi. ENE of Lucerne Valley 5/24 6:56 pm 34 23.5 118 39.1 2.5 5 mi. W of Valencia 5/24 10:57 pm 33 9.5 115 38.6 2.0 Under Obsidian Butte 5/25 3:18 am 34 37.2 116 38.4 2.3 21 mi. NE of Lucerne Valley 5/25 4:33 pm 33 24.5 118 7.9 2.3 11 mi. ENE of Avalon, Catalina Island 5/26 9:43 am 34 18.5 118 33.4 2.1 4 mi. NW of Granada Hills 5/26 11:05 am 32 53.4 117 45.7 2.0 30 mi. SW of Oceanside 5/26 3:16 pm 34 16.2 116 26.9 2.3 10 mi. N of Yucca Valley 5/26 6:35 pm 34 1.1 117 6.7 2.0 4 mi. SE of Redlands 5/26 7:39 pm 35 45.0 117 37.8 2.0 9 mi. NNE of Ridgecrest 5/27 1:57 am 33 50.2 117 0.2 2.1 6 mi. NNW of Hemet 5/27 4:35 am 35 7.0 117 1.4 2.5 15 mi. N of Barstow 5/27 4:39 am 35 6.8 117 1.3 2.0 " 5/27 2:38 pm 35 45.9 117 44.0 2.4 10 mi. NNW of Ridgecrest 5/27 5:33 pm 34 13.5 118 34.2 2.1 2 mi. WSW of Northridge 5/27 7:48 pm 34 14.5 118 40.0 2.1 3 mi. SE of Simi Valley 5/27 10:37 pm 34 21.4 116 27.4 2.0 16 mi. N of Yucca Valley 5/28 7:33 am 34 9.1 116 24.9 2.3 2 mi. NE of Yucca Valley 5/28 12:13 pm 34 20.0 118 27.4 2.4 3 mi. NNW of San Fernando 5/28 1:47 pm 34 27.6 116 30.3 2.4 23 mi. N of Yucca Valley 5/28 5:43 pm 34 12.9 118 35.2 1.8 1 mi. NE of Canoga Park 5/28 6:08 pm 35 35.5 116 53.4 3.0 16 mi. N of Goldstone Lake 5/29 3:21 am 33 57.4 117 49.6 2.4 3 mi. SSW of Diamond Bar 5/29 3:29 am 35 44.3 117 38.0 2.4 8 mi. NNE of Ridgecrest 5/29 4:01 am 33 12.7 115 36.0 2.7 3 mi. NE of Obsidian Butte 5/29 4:01 am 33 59.5 116 28.0 2.3 2 mi. NE of Desert Hot Springs -------------------------------------------------------------