SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey January 4, 1996 Weekly Earthquake Report for Southern California ------------------------------------------------ December 28, 1995 - January 3, 1996 Prepared by: Kate Hutton, Seismological Laboratory (kate@bombay.gps.caltech.edu) 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, December 28, Universal Time (ie. GMT), to midnight Wednesday night, January 3, 1995, Universal Time. In local time, the period of coverage is from 4 p.m., December 27 to 4 p.m., January 3, Pacific Standard Time. We detected and processed 341 earthquakes during the 7-day period covered. 1995 ended with moderately low seismicity. The highlight of the week was a M4.0, with aftershocks, not far from the Garlock Fault near the town of Mojave, on Sunday afternoon. This events and it's largest aftershock about 1 hour later both have strike-slip focal mechanisms, but with a stike different than the Garlock itself. The M4.0 occurred on Sunday afternoon and was apparently not felt. There were also several M3 events, including: a M3.0 Landers aftershock last Wednesday evening; a M3.0, which was felt, in Cajon Pass on Thursday afternoon; a M3.3 Northridge aftershock, which was felt, early on New Years Day. It is time for the fourth quarter 1995 seismicity summary. The total seismicity rate can be seen and compared to previous quarters with the following table: 1st quarter 2nd quarter 3rd quarter 4th quarter all 3.0+ all 3.0+ all 3.0+ all 3.0+ 1990 3,483 56 2,627 45 2,225 27 2,403 31 1991 2,041 11 2,218 32 2,445 23 2,651 29 1992 3,618 40 10,288 744 25,500+ 801 10,700+ 166 1993 4,939 43 5,370 61 5,298 48 4,583 35 1994 10,915 417 5,967 43 5,400 48 5,031 40 1995 3,815 28 3,982 39 8,259 90 7,743 51 Totals are listed for all events in the core area of the Seismo- graphic Network and also for a subset of events of M3 and larger. Statistics on the major earthquake sequences are as follows: Northridge ---------- 1/17/94 - 12/31/95 Latitude 34.1 - 34.5 North, Longitude 118.3 - 118.85 West All events 12,548 (324 more this quarter) 3.0 - 3.9 382 4.0 - 4.9 48 5.0 and up 10 Landers/Big Bear ---------------- 4/23/92 - 12/31/95 Latitude 33.8 - 35.33 North, Longitude 116.0 - 117.05 West All events 59,000+ (1,513 more this quarter) 3.0 - 3.9 1,560 4.0 - 4.9 166 5.0 and up 22 Ridgecrest ---------- 8/17/95 - 12/31/95 Latitude 35.65 - 35.85 North, Longitude 117.55 - 117.75 West All events 8,402 (3,890 more this quarter) 3.0 - 3.9 75 4.0 - 4.9 9 5.0 and up 2 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 ------------------------------------------------------------- 12/27 7:06 pm 34 34.4 116 18.4 2.6 30 mi. N of Joshua Tree 12/27 8:05 pm 35 44.3 117 37.9 2.7 8 mi. NNE of Ridgecrest 12/27 8:06 pm 34 36.2 116 37.9 3.0 20 mi. ENE of Lucerne Valley 12/27 9:56 pm 32 50.8 116 6.0 2.9 9 mi. NW of Ocotillo 12/28 3:48 am 33 9.1 116 30.5 2.1 7 mi. NE of Julian 12/28 5:32 am 34 13.3 118 35.2 2.0 1 mi. NE of Canoga Park 12/28 6:54 am 34 14.0 117 27.6 3.0 3 mi. WNW of Devore FELT 12/28 9:33 am 35 44.3 117 38.1 2.5 8 mi. NNE of Ridgecrest 12/29 4:05 am 34 7.8 116 59.3 2.3 7 mi. NNE of Yucaipa 12/29 4:19 pm 35 46.9 117 38.9 2.0 11 mi. N of Ridgecrest 12/30 2:00 am 34 22.0 118 37.7 2.0 4 mi. WSW of Valencia 12/30 2:11 am 32 27.8 115 32.5 2.2 14 mi. S of Calexico 12/30 2:17 am 32 28.2 115 32.4 2.2 13 mi. S of Calexico 12/30 3:04 pm 34 13.4 118 35.2 2.6 1 mi. NNE of Canoga Park 12/30 3:43 pm 35 46.3 117 38.8 2.0 10 mi. N of Ridgecrest 12/30 4:44 pm 34 18.1 118 27.5 2.3 1 mi. NW of Pacoima 12/30 8:13 pm 33 16.4 115 59.1 2.4 1 mi. WSW of Salton City 12/31 12:13 pm 35 5.6 118 18.6 2.4 8 mi. ESE of Tehachapi 12/31 1:48 pm 35 5.9 118 18.3 4.0 8 mi. WNW of Mojave 12/31 2:48 pm 35 5.9 118 18.4 2.5 8 mi. ESE of Tehachapi 12/31 2:51 pm 35 5.8 118 18.3 3.3 8 mi. WNW of Mojave 12/31 3:20 pm 35 44.1 117 37.9 2.1 8 mi. NNE of Ridgecrest 12/31 5:08 pm 34 18.1 117 3.7 2.0 7 mi. NNE of Running Springs 12/31 9:33 pm 34 22.9 116 27.2 2.5 18 mi. N of Yucca Valley 1/1 1:21 am 33 4.4 117 51.8 2.1 28 mi. SSW of Dana Point 1/1 3:33 am 35 5.8 118 18.8 2.3 7 mi. ESE of Tehachapi 1/1 6:53 am 34 20.1 118 36.0 3.3 4 mi. SSW of Valencia FELT 1/1 10:54 am 35 5.6 118 19.0 2.0 7 mi. ESE of Tehachapi 1/1 4:35 pm 33 0.3 117 44.7 2.1 24 mi. WSW of Oceanside 1/1 10:04 pm 35 44.1 117 39.7 2.0 7 mi. N of Ridgecrest 1/1 10:14 pm 34 38.5 116 39.4 2.7 21 mi. NE of Lucerne Valley 1/1 11:38 pm 34 17.2 118 32.1 2.4 2 mi. WNW of Granada Hills 1/2 12:05 am 32 47.6 115 27.0 2.1 5 mi. E of El Centro 1/2 3:02 am 34 10.2 116 26.3 2.2 3 mi. N of Yucca Valley 1/2 5:35 am 34 17.9 116 26.9 2.2 12 mi. N of Yucca Valley 1/2 7:59 am 34 10.3 116 26.2 2.2 3 mi. N of Yucca Valley 1/2 9:37 am 34 10.3 116 26.1 2.6 3 mi. N of Yucca Valley 1/2 11:44 pm 33 56.6 116 54.7 2.3 2 mi. WNW of Banning 1/3 6:38 am 35 7.2 118 37.6 2.0 10 mi. W of Tehachapi 1/3 9:50 am 34 18.9 118 24.8 2.5 2 mi. NNE of San Fernando -------------------------------------------------------------