SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey May 18, 1995 Weekly Earthquake Report for Southern California ------------------------------------------------ May 11 - 17, 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, May 11, Pacific Daylight Time, to midnight Wednesday night, May 17, 1995, Pacific Daylight Time. We recorded 273 earthquakes of M1.0 or larger during the 7-day period covered. We are back to our typical quiet this week. The largest quake was a M3.8 in the San Gorgonio Pass area, near Beaumont. It could easily have been felt in the Redlands and San Bernardino area; however, we got no calls. This event was quite typical for the region, which is one of the most active in southern California. The quake was located near the Banning fault, west of the area where the Banning may be the active strand of the San Andreas fault. It occurred at 14 km depth and had a focal mechanism showing oblique reverse slip. One plane was parallel to the Banning fault (20 deg north of west), dipped 70 deg to the north and had about half right- lateral and half reverse slip. Two Northridge aftershocks, both in the Potrero Canyon area, southwest of Magic Mountain, and both M2.8, were felt. The first was on Tuesday evening and the second on Wednesday morning. They were felt in Simi Valley and the northern San Fernando Valley. 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 ------------------------------------------------------------- 5/11 4:21 am 34 15.0 118 27.0 2.4 2 mi. SSW of San Fernando 5/11 9:24 am 35 50.8 117 38.0 2.8 15 mi. N of Ridgecrest 5/11 10:01 am 34 16.4 116 45.4 2.3 5 mi. E of Big Bear City 5/11 1:09 pm 33 51.9 116 12.9 2.0 10 mi. N of Indio 5/11 2:29 pm 33 47.9 118 8.1 2.0 2 mi. NE of downtown Long Beach 5/11 2:34 pm 32 0.7 115 45.6 2.5 47 mi. SSW of Calexico 5/12 8:10 am 33 54.5 116 17.8 2.1 14 mi. NNW of Indio 5/12 11:22 am 34 9.1 116 26.0 2.4 2 mi. NNE of Yucca Valley 5/12 11:40 am 34 22.6 116 27.7 2.3 17 mi. N of Yucca Valley 5/12 5:20 pm 35 16.2 118 36.2 2.1 13 mi. NW of Tehachapi 5/12 7:19 pm 34 6.0 117 18.1 2.1 Under downtown San Bernardino 5/12 7:25 pm 33 58.5 116 58.4 3.8 3 mi. N of Beaumont 5/12 8:24 pm 33 13.3 116 13.9 2.4 7 mi. NW of Ocotillo Wells 5/13 12:22 am 32 22.0 115 22.1 2.5 22 mi. SSE of Calexico 5/13 8:45 am 34 18.4 117 49.5 2.2 2 mi. SE of Crystal Lake 5/13 1:29 pm 34 38.2 116 39.8 2.8 20 mi. NE of Lucerne Valley 5/13 4:46 pm 34 57.6 116 56.2 2.2 7 mi. NE of Barstow 5/13 7:13 pm 34 15.4 116 27.2 2.2 9 mi. N of Yucca Valley 5/14 12:36 am 33 20.8 116 25.7 2.0 7 mi. NNW of Borrego Springs 5/14 12:38 am 34 39.4 116 32.9 2.0 26 mi. ENE of Lucerne Valley 5/14 3:39 am 34 59.0 116 56.9 2.2 7 mi. NNE of Barstow 5/14 5:03 am 34 20.0 116 27.8 2.1 14 mi. N of Yucca Valley 5/14 1:51 pm 34 50.5 116 39.4 2.1 21 mi. E of Barstow 5/14 8:58 pm 35 24.5 117 48.6 2.4 16 mi. SSW of Ridgecrest 5/15 1:11 am 34 28.5 116 30.3 2.1 24 mi. N of Yucca Valley 5/15 6:37 am 33 7.0 119 4.9 2.2 24 mi. S of Santa Barbara Is. 5/15 12:44 pm 34 22.1 116 27.8 2.3 17 mi. N of Yucca Valley 5/15 1:07 pm 33 53.7 116 12.5 2.0 12 mi. N of Indio 5/15 2:59 pm 34 21.5 118 37.6 2.4 5 mi. SSW of Magic Mtn. 5/15 3:27 pm 33 54.3 116 17.8 2.5 13 mi. NNE of Palm Desert 5/16 7:48 am 33 53.4 116 12.6 2.0 12 mi. N of Indio 5/16 10:15 am 34 37.8 116 30.2 2.2 28 mi. ENE of Lucerne Valley 5/16 7:19 pm 34 23.2 118 39.3 2.1 4 mi. SW of Magic Mtn. 5/16 7:22 pm 34 23.2 118 39.5 2.8 " FELT 5/17 12:11 am 34 22.5 116 27.8 2.4 17 mi. N of Yucca Valley 5/17 12:41 am 35 57.8 117 22.6 2.3 13 mi. N of Trona 5/17 3:20 am 33 54.8 118 36.5 2.2 9 mi. SSE of Malibu 5/17 7:52 am 35 50.9 120 23.7 2.3 4 mi. SSE of Parkfield 5/17 9:53 am 34 23.3 118 39.3 2.8 4 mi. SW of Magic Mtn. FELT 5/17 10:02 pm 33 57.7 116 19.6 2.1 10 mi. E of Desert Hot Springs -------------------------------------------------------------