SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey March 27, 1997 Weekly Earthquake Report for Southern California ------------------------------------------------ March 20 - 26, 1997 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 818-395-6327. For daily updates, call our Earthquake Information Hotline: 818-395-6977. -------------------------------- This week's Report covers the time period from midnight Thursday morning, March 20, Universal Time (ie. GMT), to midnight Wednesday night, March 26, Universal Time. In local time, the period of coverage is from 4 p.m., March 19, Pacific Standard Time, to 4 p.m., March 26, Pacific Standard Time. We detected and processed 301 earthquakes during the seven-day period covered. There was only one M3+ this week: a M3.1 near Hemet last Thursday morning. It occurred in the complex San Jacinto Fault zone, which is a common source of seismic activity. The focal mechanism is the expected strike-slip parallel to the San Jacinto, with a small thrust component. We did not receive any inquiries about this quake. Other activity included the usual assortment of Landers, Northridge, Ridgecrest, and Coso aftershocks. M2.9, on Friday afternoon, was the largest aftershock to last week's "Calico" aftershock of Landers. Table 1 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 ------------------------------------------------------------- 3/19 7:08 pm 36 45.8 118 34.5 2.4 20 mi. NW of Mt. Whitney 3/19 10:57 pm 34 58.7 116 49.7 2.0 12 mi. ENE of Barstow 3/20 8:32 am 34 13.5 118 31.4 2.6 Under Northridge 3/20 9:59 am 35 2.4 116 47.7 2.0 16 mi. NE of Barstow 3/20 10:12 am 33 48.5 116 58.4 3.1 4 mi. N of Hemet 3/20 10:37 am 34 1.0 117 10.4 2.2 2 mi. S of Redlands 3/20 2:59 pm 33 11.0 118 21.3 2.2 11 mi. S of Avalon, Catalina Island 3/20 3:29 pm 34 57.9 116 49.3 2.1 12 mi. ENE of Barstow 3/20 8:06 pm 34 58.0 116 49.6 2.5 " 3/20 9:47 pm 34 58.3 116 49.2 2.0 " 3/20 10:22 pm 34 27.5 120 47.5 2.2 11 mi. SW of Pt. Arguello 3/21 3:20 am 35 43.3 117 40.9 2.1 6 mi. N of Ridgecrest 3/21 3:30 am 34 13.2 118 26.7 2.2 Under Panorama City 3/21 6:23 am 34 58.4 116 48.9 2.1 13 mi. ENE of Barstow 3/21 12:27 pm 32 6.0 117 28.5 2.5 40 mi. SW of San Ysidro 3/21 3:03 pm 36 5.9 117 39.7 2.5 16 mi. E of Coso Junction 3/21 4:53 pm 34 58.3 116 49.1 2.9 12 mi. ENE of Barstow 3/21 9:49 pm 36 5.8 117 39.8 2.2 16 mi. E of Coso Junction 3/21 10:18 pm 33 29.0 116 27.5 2.2 13 mi. ESE of Anza 3/22 4:17 am 34 32.1 118 57.3 2.0 9 mi. NNW of Fillmore 3/22 9:31 am 33 31.0 116 31.2 2.0 9 mi. ESE of Anza 3/22 1:12 pm 32 37.4 115 54.8 2.1 9 mi. SSE of Ocotillo 3/23 12:13 am 34 17.0 118 42.5 2.1 Under Simi Valley 3/23 12:27 pm 34 30.1 116 31.0 2.5 26 mi. N of Yucca Valley 3/23 6:11 pm 35 56.2 117 13.6 2.7 14 mi. NE of Trona 3/23 7:16 pm 35 47.2 117 37.6 2.0 11 mi. N of Ridgecrest 3/24 12:24 am 36 51.1 117 25.1 2.2 22 mi. NW of Stovepipe Wells 3/24 6:20 am 34 5.4 116 42.8 2.0 6 mi. E of Mt. San Gorgonio 3/24 6:21 pm 34 1.4 116 19.4 2.2 7 mi. S of Joshua Tree 3/24 9:30 pm 34 3.1 117 15.4 2.2 Under Loma Linda 3/24 11:15 pm 33 52.1 119 23.6 2.3 13 mi. SSE of Santa Cruz Is. 3/25 1:41 am 32 42.7 117 56.7 2.5 24 mi. ESE of San Clemente Is. 3/25 10:17 am 33 58.4 117 3.7 2.0 4 mi. SSW of Yucaipa 3/25 1:45 pm 34 56.4 116 44.8 2.1 16 mi. ENE of Barstow 3/25 3:50 pm 36 15.7 120 23.4 2.2 8 mi. N of Coalinga 3/26 9:17 am 34 9.4 116 25.6 2.0 2 mi. NNE of Yucca Valley -------------------------------------------------------------