SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey January 25, 1996 Weekly Earthquake Report for Southern California ------------------------------------------------ January 18 - 24, 1996 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, January 18, Universal Time (ie. GMT), to midnight Wednesday night, January 14, 1995, Universal Time. In local time, the period of coverage is from 4 p.m., January 17 to 4 p.m., January 14, Pacific Standard Time. We detected and processed 387 earthquakes during the 7-day period covered. Seismicity has slowed down considerably, mainly due to the decline of the Ridgecrest sequence. The second figure summarizes what we've seen from Ridgecrest in previous weeks. The January swarm seems to have been in the same location as the swarms last August and September. Last week, the Ridgecrest sequence contained 50 or so earthquakes that had an odd long-period appearance. Careful relocation of these events showed them to be significantly shallower than the rest of the Ridgecrest sequence, and it is now thought that their appearance was caused by their having originated in the sediments of Indian Wells Valley and NOT because of magma movement, which can also cause long-period earthquakes. There were only three M3+ events during the time period covered by this report, and the only one of these that was felt was Landers aftershock (of the June 28, 1992 Mw7.3 shock) near Yucca Valley very early Sunday morning. The other two were a Ridgecrest M3.2 last Thursday afternoon and a M3.1 under Cuyama Valley, south-southwest of Taft. 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 ------------------------------------------------------------- 1/17 10:37 pm 35 45.0 117 37.0 2.0 9 mi. NNE of Ridgecrest 1/17 11:33 pm 34 21.4 118 27.0 2.0 4 mi. N of San Fernando 1/17 11:33 pm 34 21.3 118 27.1 2.1 " 1/18 3:30 am 33 32.9 119 2.8 2.2 5 mi. N of Santa Barbara Is. 1/18 6:29 am 34 25.0 116 28.6 2.0 20 mi. N of Yucca Valley 1/18 9:40 am 35 44.8 117 37.2 2.2 9 mi. NNE of Ridgecrest 1/18 10:06 am 35 45.0 117 38.3 2.0 " 1/18 11:48 am 34 36.2 116 37.5 2.2 21 mi. ENE of Lucerne Valley 1/18 12:17 pm 35 44.7 117 37.1 3.2 8 mi. NNE of Ridgecrest 1/18 2:30 pm 34 46.9 118 53.6 2.3 2 mi. WSW of Gorman 1/18 8:13 pm 34 18.3 116 28.8 2.1 13 mi. N of Yucca Valley 1/18 10:41 pm 34 21.7 118 27.0 2.1 5 mi. N of San Fernando 1/19 2:20 am 35 47.1 117 37.6 2.2 11 mi. N of Ridgecrest 1/19 2:44 am 35 45.2 117 37.7 2.0 9 mi. NNE of Ridgecrest 1/19 1:21 pm 34 25.2 116 29.3 2.0 20 mi. N of Yucca Valley 1/19 4:50 pm 35 45.9 117 38.8 2.4 9 mi. N of Ridgecrest 1/19 8:32 pm 35 44.5 117 37.5 2.4 8 mi. NNE of Ridgecrest 1/20 1:15 am 34 14.7 118 41.1 2.2 2 mi. SSE of Simi Valley 1/20 4:29 am 35 46.0 117 39.5 2.0 9 mi. N of Ridgecrest 1/20 10:29 am 32 41.4 118 5.2 2.5 17 mi. ESE of San Clemente Is. 1/20 12:25 pm 35 45.4 117 38.4 2.0 9 mi. N of Ridgecrest 1/20 2:58 pm 35 2.1 116 60.0 2.5 10 mi. N of Barstow 1/20 3:10 pm 35 2.2 116 60.0 2.5 " 1/20 4:29 pm 35 45.4 117 38.2 2.1 9 mi. N of Ridgecrest 1/20 9:18 pm 35 47.1 118 2.2 2.1 18 mi. SSW of Coso Junction 1/21 12:55 am 33 58.7 116 51.0 2.5 3 mi. NNE of Banning 1/21 2:20 am 34 10.0 116 27.7 2.0 3 mi. NNW of Yucca Valley 1/21 4:01 am 34 5.8 116 26.7 3.2 1 mi. S of Yucca Valley FELT 1/21 1:02 pm 35 45.0 117 37.6 2.3 9 mi. NNE of Ridgecrest 1/21 8:00 pm 36 15.8 120 15.0 2.5 10 mi. NE of Coalinga 1/21 10:33 pm 34 5.8 116 38.4 2.0 4 mi. NW of Morongo Valley 1/22 11:13 am 34 5.8 116 38.5 2.5 " 1/22 4:42 pm 34 0.6 118 6.1 2.0 3 mi. WSW of Whittier Narrows Rec. Area 1/23 7:10 am 33 58.0 116 23.5 2.1 6 mi. E of Desert Hot Springs 1/23 8:54 am 34 30.1 118 40.5 2.6 3 mi. WSW of Castaic Lake 1/23 1:09 pm 35 47.4 117 40.3 2.6 11 mi. N of Ridgecrest 1/23 1:23 pm 35 45.3 117 38.1 2.2 9 mi. N of Ridgecrest 1/23 3:02 pm 33 38.9 116 43.0 2.1 6 mi. S of Idyllwild 1/23 8:08 pm 35 45.0 117 37.0 2.3 9 mi. NNE of Ridgecrest 1/23 11:42 pm 34 8.5 117 34.1 2.1 2 mi. NNE of Rancho Cucamonga 1/23 11:56 pm 34 55.2 119 33.7 3.1 16 mi. SSW of Taft 1/23 11:57 pm 35 35.1 118 28.0 2.2 3 mi. S of town of Lake Isabella 1/24 3:05 am 33 2.5 117 46.2 2.0 27 mi. SSW of San Clemente 1/24 11:02 am 33 19.0 118 0.3 2.9 21 mi. SSW of Newport Beach 1/24 2:22 pm 35 2.4 117 11.1 2.1 13 mi. NW of Barstow 1/24 3:41 pm 34 36.5 116 34.2 2.1 24 mi. ENE of Lucerne Valley 1/24 3:50 pm 34 40.3 120 49.2 2.0 11 mi. NW of Pt. Arguello -------------------------------------------------------------