SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey September 7, 1995 Weekly Earthquake Report for Southern California ------------------------------------------------ August 31 - September 6, 1995 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 818-395-6326. For daily updates, call our Earthquake Information Hotline: 818-395-6977. -------------------------------- This week's Report covers the time period from midnight Thursday morning, August 31, Pacific Daylight Time, to midnight Wednesday night, September 6, 1995, Pacific Daylight Time. We recorded 581 earthquakes during the 7-day period covered. The earthquake rate continues higher than it has been in recent months, mainly due to aftershocks of the August 17, 1995 ML5.4 Ridgecrest earthquake. 353 of our 581 fall into this catagory. The largest event of the week, however, was a ML4.4 aftershock of the June 28, 1992 Landers earthquake (Mw7.3). It occurred on Tuesday afternoon, about 5 miles N of Yucca Valley, and was felt throughout the Inland Empire and Coachella Valley. The focal mechanism is right-lateral strike-slip, just like all the other major Landers quakes. This quake had a ML3.0 aftershock about an hour and 20 minutes later that was also felt. Referring back to the January 5, 1995 issue of the Weekly Report, we expected to see about three M4+ Landers aftershocks this year, of which the Tuesday quake was the second. The first was a ML4.8 on May 7. An earlier M3.0 Landers aftershock, at a different location, was felt last Thursday morning. There was also a small (M2.5) Northridge aftershock in Reseda early Saturday morning that was felt. 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 ------------------------------------------------------------- 8/31 12:46 am 35 47.2 117 38.4 2.4 11 mi. N of Ridgecrest 8/31 1:50 am 35 47.2 117 38.7 2.3 " 8/31 4:42 am 34 22.8 116 27.3 3.0 18 mi. N of Yucca Valley FELT 8/31 5:12 am 35 24.3 117 45.4 2.2 15 mi. SSW of Ridgecrest 8/31 7:56 am 35 46.0 117 39.8 2.0 10 mi. N of Ridgecrest 8/31 9:47 am 34 55.4 116 55.5 2.5 6 mi. ENE of Barstow 8/31 1:33 pm 36 33.3 117 57.1 2.3 7 mi. ESE of Lone Pine 9/1 1:50 am 33 58.2 117 13.5 2.2 5 mi. SSE of Loma Linda 9/1 2:58 am 35 47.9 117 37.7 2.6 12 mi. N of Ridgecrest 9/1 10:05 am 33 39.3 119 1.9 2.1 12 mi. N of Santa Barbara Is. 9/1 3:33 pm 33 20.9 116 26.2 2.5 7 mi. NNW of Borrego Springs 9/1 3:55 pm 35 47.5 117 40.1 2.2 11 mi. N of Ridgecrest 9/1 5:26 pm 35 47.7 117 37.9 2.0 12 mi. N of Ridgecrest 9/2 4:04 am 34 11.6 118 33.5 2.5 1 mi. WSW of Reseda FELT 9/2 4:22 am 35 47.5 117 38.2 2.8 11 mi. N of Ridgecrest 9/2 11:55 am 34 9.1 117 42.7 2.0 3 mi. NNE of Claremont Colleges 9/2 1:01 pm 35 48.0 117 37.9 2.8 12 mi. N of Ridgecrest 9/2 6:51 pm 35 47.8 117 38.7 2.0 " 9/2 10:03 pm 33 53.7 116 50.0 2.5 3 mi. SE of Banning 9/2 11:46 pm 35 46.6 117 38.2 2.0 10 mi. N of Ridgecrest 9/3 5:08 am 34 6.3 116 55.5 2.0 5 mi. W of Mt. San Gorgonio 9/3 6:33 am 35 44.5 117 52.1 2.8 14 mi. NW of Ridgecrest 9/3 7:50 am 35 47.9 117 38.2 2.7 12 mi. N of Ridgecrest 9/3 9:05 am 35 46.7 117 38.3 2.8 10 mi. N of Ridgecrest 9/3 11:11 am 35 47.0 117 40.3 3.2 11 mi. N of Ridgecrest 9/3 11:37 am 34 55.9 118 59.3 2.4 3 mi. WSW of Grapevine 9/3 9:33 pm 35 47.6 117 38.6 2.0 11 mi. N of Ridgecrest 9/3 11:04 pm 34 37.6 116 38.5 2.2 21 mi. NE of Lucerne Valley 9/4 3:43 am 35 48.0 117 38.1 2.0 12 mi. N of Ridgecrest 9/4 10:37 pm 34 10.8 116 49.1 2.0 5 mi. N of Mt. San Gorgonio 9/5 12:32 am 35 45.5 117 40.4 2.4 9 mi. N of Ridgecrest 9/5 5:38 am 35 48.0 117 38.1 2.0 12 mi. N of Ridgecrest 9/5 12:18 pm 33 5.3 117 50.9 2.3 26 mi. SSW of Dana Point 9/5 12:38 pm 35 45.7 117 40.5 2.3 9 mi. N of Ridgecrest 9/5 1:27 pm 34 11.9 116 26.3 4.4 5 mi. N of Yucca Valley FELT 9/5 1:30 pm 34 10.9 116 25.9 2.1 " 9/5 1:32 pm 34 11.7 116 26.1 2.4 " 9/5 1:40 pm 34 11.4 116 25.8 2.2 4 mi. N of Yucca Valley 9/5 1:42 pm 34 9.9 116 25.8 2.1 3 mi. NNE of Yucca Valley 9/5 2:46 pm 34 11.8 116 26.1 2.0 5 mi. N of Yucca Valley 9/5 2:47 pm 34 15.1 116 26.2 2.3 9 mi. N of Yucca Valley 9/5 2:47 pm 34 10.7 116 25.8 3.0 4 mi. NNE of Yucca Valley FELT 9/5 3:19 pm 35 8.1 116 52.3 2.3 15 mi. S of Goldstone Lake 9/5 4:32 pm 34 11.9 116 26.2 2.2 5 mi. N of Yucca Valley 9/5 6:56 pm 34 12.0 116 26.3 2.2 " 9/6 12:55 am 34 11.1 116 25.6 2.0 4 mi. NNE of Yucca Valley 9/6 7:43 am 35 46.9 117 40.0 2.6 11 mi. N of Ridgecrest 9/6 8:41 am 35 46.0 117 39.1 2.1 10 mi. N of Ridgecrest 9/6 9:14 am 35 46.5 117 39.1 2.4 " 9/6 11:12 am 33 55.7 118 31.8 2.6 5 mi. WSW of Los Angeles Airport 9/6 2:35 pm 35 45.6 117 38.7 2.2 9 mi. N of Ridgecrest 9/6 3:55 pm 34 12.6 116 26.2 2.1 6 mi. N of Yucca Valley 9/6 4:54 pm 34 56.8 119 16.6 2.7 16 mi. SE of Taft 9/6 5:06 pm 35 45.8 117 38.4 2.2 9 mi. N of Ridgecrest 9/6 8:58 pm 34 58.5 119 6.3 2.6 9 mi. WSW of Wheeler Ridge -------------------------------------------------------------