September 8, 1994 Weekly Earthquake Report for Southern California ------------------------------------------------ September 1 - 7, 1994 Prepared by: Kate Hutton, Seismological Laboratory (kate@bombay.gps.caltech.edu) Lucy Jones, U.S. Geological Survey California Institute of Technology This document is a commentary on current seismic activity. The earthquakes discussed have been detected and processed automatically. All epicenters and magnitudes have been reviewed to exclude obvious blunders; however, they must still be considered preliminary. 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, September 1, Pacific Daylight Time, to midnight Wednesday night, September 7, Pacific Daylight Time. We recorded 338 earthquakes this week. Both of the quakes that were felt this week were Northridge aftershocks: a M2.7 on Monday afternoon, near San Fernando, and a a M2.7 late Tuesday afternoon, near Canoga Park. No aftershocks, to the Northridge or to the Landers earthquakes, were above M3.0. There were two M3+ events in the Coalinga/Parkfield area, on Tuesday morning (M3.1) and on Wednesday afternoon (M3.0). If you need further information on these quakes, see the Northern California Earthquake Report or contact the U.S. Geological Survey in Menlo Park (415-864-8300). Another event of interest, a M4.1 southwest of Modesto on Wednesday, occurred in the Menlo Park coverage area. There were 16 more events in the on-going Fontana swarm, but the largest was M2.0. None of them were apparently felt. The table lists the quakes 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 Daylight Time listed. Table 1 ------- Date Time N Lat. W Long. Mag ------------------------------------------------------------- 9/1 3:24 am 34 1.9 117 30.3 2.0 Fontana, 3 mi. SE of the I10/I15 interchange 9/1 8:31 am 34 13.0 118 39.0 2.7 2 mi. WNW of Canoga Park 9/1 9:07 am 34 50.0 116 18.8 2.0 32 mi. SSW of Baker 9/1 9:39 am 34 19.3 116 25.5 2.0 14 mi. N of Yucca Valley 9/1 3:33 pm 34 23.9 116 27.8 2.2 19 mi. N of Yucca Valley 9/2 1:59 am 34 6.8 117 26.6 2.0 Under Fontana 9/2 2:57 am 34 2.5 117 30.7 2.0 Fontana, 2 mi. SE of the I10/I15 interchange 9/2 5:32 am 34 12.9 118 38.4 2.0 2 mi. WNW of Canoga Park 9/2 5:49 am 34 2.6 117 30.6 2.0 Fontana, 2 mi. SE of the I10/I15 interchange 9/2 7:35 am 34 15.6 118 28.3 2.0 2 mi. SW of San Fernando 9/2 7:49 am 34 20.5 116 28.5 2.0 15 mi. N of Yucca Valley 9/2 10:00 am 34 13.2 118 38.8 2.1 2 mi. WNW of Canoga Park 9/2 2:31 pm 34 18.9 118 45.9 2.0 4 mi. NW of Simi Valley 9/2 7:26 pm 34 8.4 116 25.5 2.3 1 mi. NE of Yucca Valley 9/3 12:00 am 34 9.0 116 25.8 2.5 2 mi. NNE of Yucca Valley 9/3 3:00 am 35 48.5 117 57.4 2.0 16 mi. S of Coso Junction 9/3 7:25 am 34 32.8 118 51.2 2.0 11 mi. NNE of Fillmore 9/3 8:57 am 34 55.4 116 33.9 2.0 26 mi. E of Barstow 9/3 10:06 am 34 55.4 116 32.7 2.0 " 9/3 2:27 pm 33 20.9 116 20.9 2.2 6 mi. NNE of Borrego Springs 9/3 2:52 pm 34 35.2 116 35.3 2.0 22 mi. ENE of Lucerne Valley 9/3 4:29 pm 32 39.1 115 53.8 2.2 8 mi. SE of Ocotillo 9/3 6:52 pm 34 18.6 116 26.4 2.1 13 mi. N of Yucca Valley 9/4 1:33 am 34 0.7 117 6.4 2.2 4 mi. SE of Redlands 9/4 2:12 am 34 32.5 116 32.0 2.0 26 mi. NE of Big Bear City 9/4 8:33 am 35 29.5 118 26.9 2.0 10 mi. S of the town of Lake Isabella 9/4 9:57 am 34 16.7 116 42.1 2.2 8 mi. E of Big Bear City 9/4 12:43 pm 35 7.4 116 40.5 2.3 19 mi. SE of Goldstone (dry) Lake 9/4 1:26 pm 34 19.9 118 28.8 2.0 4 mi. NW of San Fernando 9/4 1:26 pm 34 19.9 118 28.9 2.3 " 9/5 2:32 am 34 18.2 118 27.5 2.5 1 mi. NW of San Fernando 9/5 7:59 am 33 58.6 116 19.1 2.1 10 mi. E of Desert Hot Springs 9/5 9:59 am 34 41.6 119 17.2 2.1 17 mi. N of Ojai 9/5 1:27 pm 34 18.4 118 25.5 2.6 1 mi. NNE of San Fernando FELT 9/5 4:40 pm 34 58.9 116 56.7 2.2 7 mi. NE of Barstow 9/5 8:12 pm 34 7.7 116 54.3 2.0 4 mi. WNW of Mt. San Gorgonio 9/6 7:02 am 32 47.2 115 26.8 2.4 6 mi. E of El Centro 9/6 7:51 am 32 45.7 118 23.0 2.9 4 mi. SSW of San Clemente Is. 9/6 8:29 am 36 9.2 120 30.2 3.1 8 mi. WNW of Coalinga 9/6 9:55 am 32 47.0 115 26.6 2.2 6 mi. E of El Centro 9/6 10:04 am 34 2.8 117 30.6 2.0 Fontana, 2 mi. SE of the I10/I15 interchange 9/6 5:45 pm 34 12.7 118 38.5 2.7 2 mi. WNW of Canoga Park FELT 9/6 9:38 pm 34 16.4 118 27.2 2.2 1 mi. WSW of San Fernando 9/6 10:01 pm 34 43.0 116 5.3 2.3 37 mi. S of Baker 9/7 2:41 am 34 22.1 116 28.1 2.1 17 mi. N of Yucca Valley 9/7 2:08 pm 35 2.3 116 59.9 2.8 10 mi. N of Barstow 9/7 3:34 pm 35 59.5 120 33.5 3.0 9 mi. NW of Parkfield 9/7 10:01 pm 33 57.2 116 23.7 2.1 6 mi. E of Desert Hot Springs 9/7 10:35 pm 34 15.8 118 34.5 2.0 3 mi. NW of Northridge ------------------------------------------------------------- Figure 1. A map of southern California showing the earthquakes recorded during the past week by the Caltech/USGS Seismic Network. Major faults are marked, as well as the metropolitan areas of Los Angeles (L.A.), Palm Springs (P.S.), San Diego (S.D.), and Santa Barbara (S.B.). The circles denote the earthquakes, the size of the circle indicating the magnitude.