December 22, 1994 Weekly Earthquake Report for Southern California ------------------------------------------------ December 15 - 21, 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, December 15, Pacific Standard Time, to midnight Wednesday night, December 21, Pacific Standard Time. We recorded 288 earth- quakes of M1.0 or larger during the 7-day period covered. Compared to last week, the seismicity was rather dull. The big excitement was a M5.0 at near Parkfield, which kicked us into a "C-alert" for a M6 in that area. This means about a 10% chance for the 72 hours following the M5.0, which was early on Tuesday morning. A "C-level" alert is not considered grounds for any sort of public response. Parkfield is really in Menlo Park's coverage area, however, so readers should consult the Northern California Report for further details. In this area, their locations and magnitudes should be considered superior to ours. There was one other possibly felt event in our area: a vigilant observer at the Jet Propulsion Lab may have felt a M2.5 in the Whittier Narrows area on Tuesday afternoon. He did have the time right, so it is possible. 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 ------------------------------------------------------------- 12/15 5:16 am 36 7.4 119 42.5 2.0 27 mi. WSW of Visalia 12/15 10:35 pm 34 13.4 116 45.3 2.4 6 mi. ESE of Big Bear City 12/16 3:08 am 33 14.8 116 5.1 2.1 7 mi. NNE of Ocotillo Wells 12/16 7:16 am 33 34.0 118 11.6 2.0 11 mi. SSE of Pt. Fermin, San Pedro 12/16 8:48 am 34 12.8 118 37.0 2.4 1 mi. NW of Canoga Park 12/16 11:25 am 34 58.9 116 56.8 2.3 7 mi. NE of Barstow 12/16 3:53 pm 33 18.8 118 18.8 2.3 2 mi. SSE of Avalon, Catalina Island 12/16 9:00 pm 34 22.5 116 27.7 2.2 17 mi. N of Yucca Valley 12/16 10:32 pm 35 46.3 116 14.2 2.0 14 mi. S of Shoshone 12/17 6:43 am 36 12.3 120 38.5 2.5 16 mi. WNW of Coalinga 12/17 8:57 am 34 14.7 116 26.2 2.4 8 mi. N of Yucca Valley 12/17 11:45 pm 34 9.6 117 26.5 2.2 3 mi. N of Fontana 12/18 7:08 am 33 49.4 117 44.5 2.5 5 mi. SE of Yorba Linda 12/18 9:29 am 34 25.1 119 25.1 2.1 5 mi. ENE of Carpinteria 12/18 4:59 pm 35 2.4 118 46.2 2.1 11 mi. SSE of Arvin 12/18 10:42 pm 34 26.6 116 30.8 2.1 22 mi. N of Yucca Valley 12/18 10:54 pm 34 26.2 116 30.3 2.2 " 12/19 3:06 am 35 22.8 118 38.3 2.5 16 mi. NE of Arvin 12/19 3:36 am 36 1.5 120 33.7 2.5 11 mi. NW of Parkfield 12/19 7:08 am 33 55.7 116 17.2 2.2 12 mi. E of Desert Hot Springs 12/19 7:10 am 33 55.6 116 17.4 2.2 " 12/19 9:30 am 36 9.4 118 2.2 2.2 5 mi. WNW of south end of Haiwee Reservoir 12/19 12:08 pm 35 40.2 117 40.9 2.4 3 mi. NNW of Ridgecrest 12/19 3:30 pm 35 37.1 116 15.0 2.2 24 mi. S of Shoshone 12/20 1:53 am 34 3.3 116 23.4 2.3 5 mi. SE of Yucca Valley 12/20 2:27 am 35 54.7 120 28.5 5.0 2 mi. WNW of Parkfield; FELT 12/20 3:06 am 34 28.3 117 50.5 2.3 14 mi. WNW of Wrightwood 12/20 3:13 am 34 12.8 117 35.6 2.1 6 mi. SSE of Mt. Baldy 12/20 3:51 am 34 28.3 117 50.6 2.3 14 mi. WNW of Wrightwood 12/20 4:55 am 35 54.5 120 28.7 3.3 2 mi. WNW of Parkfield 12/20 5:48 am 35 57.0 120 28.8 2.0 4 mi. NW of Parkfield 12/20 10:04 am 32 56.7 116 17.7 2.0 16 mi. SW of Ocotillo Wells 12/20 10:55 am 34 17.1 118 23.3 2.2 2 mi. E of San Fernando 12/20 2:49 pm 34 2.7 118 5.5 2.5 Whitter Narrows Recreation Area, FELT? 12/20 7:48 pm 34 15.4 118 30.7 2.0 1 mi. NE of Northridge 12/21 1:36 pm 34 14.7 118 34.8 2.2 2 mi. WNW of Northridge 12/21 2:09 pm 34 17.2 118 25.9 2.0 Under San Fernando 12/21 2:30 pm 34 58.0 117 1.7 2.0 5 mi. N of Barstow 12/21 10:03 pm 36 7.2 117 50.2 2.6 6 mi. E of Haiwee Reservoir 12/21 11:14 pm 36 6.9 117 50.5 2.0 5 mi. ESE of Haiwee Reservoir ------------------------------------------------------------- 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.