SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey March 21, 1996 Weekly Earthquake Report for Southern California ------------------------------------------------ March 14 - 20, 1996 Prepared by: Nick Scheckel, 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, March 14, Universal Time (ie. GMT), to midnight Wednesday night, March 20, Universal Time. In local time, the period of coverage is from 4 p.m., March 13 to 4 p.m., March 20, Pacific Standard Time. We detected and processed 389 earthquakes during the 7-day period covered. This week's excitement, seismically speaking, occurred Tuesday evening near Newhall. This M4.1 aftershock of the January 17th, 1994 M6.7 earthquake was the 50th aftershock measuring between M4.0 - M4.9. The last aftershock M4 or greater occurred last year on June 26th which had a magnitude of 5.0. Of course this event was widely felt in the area, so it seems appropo to restate (for readers concerned of larger aftershocks occurring so late) that though aftershocks decrease in number in time, the relative number of small to large remain the same. Many smaller, felt and unfelt aftershocks have passed since June 26th, 1995. A small swarm has begun this week near Coso Junction with numerous small events including 11 events over M2, the largest being a M2.9. This swarm is located about 30 km (20 miles) to the north of the 1995 - 1996 Ridgecrest sequence. 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 ------------------------------------------------------------- 3/13 6:40 pm 34 10.0 116 50.6 2.0 4 mi. NNW of Mt. San Gorgonio 3/13 8:55 pm 34 27.0 116 30.2 2.6 23 mi. N of Yucca Valley 3/13 9:07 pm 34 15.4 118 35.6 2.4 Under Chatsworth 3/13 10:12 pm 33 0.7 117 51.3 2.7 32 mi. SSW of Dana Point 3/14 3:27 am 33 0.3 117 50.1 2.2 " 3/14 10:16 am 34 19.8 116 28.0 2.4 14 mi. N of Yucca Valley 3/15 2:15 pm 34 32.9 116 31.6 2.0 24 mi. ENE of Lucerne Valley 3/15 4:18 pm 34 3.4 117 15.4 2.1 Under Loma Linda 3/15 4:27 pm 35 46.2 117 37.7 2.1 10 mi. NNE of Ridgecrest 3/15 7:29 pm 33 39.3 116 42.3 2.0 6 mi. S of Idyllwild 3/15 9:06 pm 35 31.6 118 25.9 2.0 7 mi. SSE of town of Lake Isabella 3/15 11:42 pm 34 20.1 116 28.1 2.1 14 mi. N of Yucca Valley 3/16 8:57 am 35 46.2 117 37.4 2.1 10 mi. NNE of Ridgecrest 3/16 1:21 pm 36 31.1 116 58.8 2.1 8 mi. WNW of Furnace Creek 3/16 3:59 pm 33 18.9 118 18.1 2.6 2 mi. SSE of Avalon, Catalina Island 3/16 8:34 pm 35 44.5 117 40.0 2.2 8 mi. N of Ridgecrest 3/16 10:14 pm 33 15.7 116 18.1 2.3 4 mi. E of Borrego Springs 3/17 12:34 pm 34 16.8 118 33.2 2.3 3 mi. NNW of Northridge 3/17 3:34 pm 33 59.2 116 55.5 2.0 4 mi. NW of Banning 3/17 5:47 pm 36 3.1 117 43.2 2.6 12 mi. E of Coso Junction 3/17 5:47 pm 36 3.1 117 42.8 2.3 13 mi. E of Coso Junction 3/17 5:48 pm 36 3.3 117 42.8 2.4 " 3/17 6:39 pm 32 51.7 118 27.4 2.0 7 mi. WNW of San Clemente Is. 3/17 7:21 pm 36 3.2 117 43.3 2.9 12 mi. E of Coso Junction 3/17 7:23 pm 36 3.2 117 43.0 2.3 " 3/17 7:27 pm 36 3.0 117 43.2 2.3 " 3/17 7:33 pm 36 3.0 117 43.3 2.0 " 3/17 7:33 pm 36 3.2 117 43.2 2.0 " 3/17 7:51 pm 36 3.3 117 43.2 2.1 " 3/17 8:07 pm 36 3.1 117 43.2 2.4 " 3/17 8:07 pm 36 3.6 117 43.6 2.3 " 3/17 10:42 pm 36 3.2 117 43.3 2.3 " 3/17 11:04 pm 34 13.7 118 27.2 2.1 Under Panorama City 3/18 12:04 am 32 39.1 118 7.8 2.0 17 mi. SE of San Clemente Is. 3/18 12:16 am 34 21.0 116 27.7 2.0 16 mi. N of Yucca Valley 3/18 3:10 pm 34 48.8 116 41.9 2.0 19 mi. ESE of Barstow 3/18 6:02 pm 34 58.7 116 57.4 2.2 7 mi. NNE of Barstow 3/18 9:56 pm 33 57.9 119 18.7 2.3 13 mi. SSW of Port Hueneme 3/19 1:35 am 33 29.3 118 12.3 2.1 12 mi. NE of Avalon, Catalina Island 3/19 12:33 pm 36 0.8 117 48.8 2.4 7 mi. ESE of Coso Junction 3/19 4:37 pm 34 19.9 116 28.2 2.2 14 mi. N of Yucca Valley 3/19 11:37 pm 34 21.7 118 36.9 4.1 5 mi. WSW of Newhall WIDELY FELT 3/19 11:40 pm 34 21.8 118 36.4 2.8 " 3/19 11:41 pm 34 21.3 118 36.8 2.4 " 3/19 11:43 pm 34 21.4 118 36.9 2.0 " 3/20 12:20 am 34 21.9 118 36.3 2.1 " 3/20 2:55 am 36 3.1 117 43.5 2.3 12 mi. E of Coso Junction 3/20 11:54 am 36 14.9 120 12.4 2.2 11 mi. NE of Coalinga 3/20 12:37 pm 33 14.7 116 12.4 2.0 8 mi. NNW of Ocotillo Wells -------------------------------------------------------------