SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey October 31, 1996 Weekly Earthquake Report for Southern California ------------------------------------------------ October 24 - 30, 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 818-395-6327. For daily updates, call our Earthquake Information Hotline: 818-395-6977. -------------------------------- This week's Report covers the time period from midnight Thursday morning, October 24, Universal Time (ie. GMT), to midnight Wednesday night, October 30, Universal Time. In local time, the period of coverage is from 5 p.m., October 13, Pacific Daylight Time, to 5 p.m., October 30, Pacific Daylight Time. We detected and processed 213 earthquakes during the seven-day period covered. We have the software bug that included quarry blasts fixed, so these should all be earthquakes. The seismicity was low this week. The largest event was a M3.5 aftershock of the Ojai quake (M4.2) that occurred last Thursday. The aftershock occurred last Thursday evening. It was felt. There was also a M3.4 Yucca Valley quake very early on Friday morning. This one was a typical Landers aftershock. Considering the propensity of Yucca Valley residents to feel small aftershocks, I would be surprised if it was not felt. But I can't seem to find any reports that it was on my desk or e-mail. The following are some belated statistics for the third quarter of 1996. They include the total number of events in each three-month time period and alsot the number that were M3.0 and larger. 1st quarter 2nd quarter 3rd quarter 4th quarter all 3.0+ all 3.0+ all 3.0+ all 3.0+ 1986 3,040 16 2,865 19 6,634 192 2,300 38 1987 1,679 24 1,887 36 2,341 38 5,748 198 1988 2,749 40 2,128 45 2,195 30 2,208 27 1989 2,528 46 2,340 21 2,323 19 2,335 26 1990 2,850 56 2,293 43 1,859 27 2,039 31 1991 1,679 10 1,843 32 2,081 21 2,337 27 1992 3,389 37 10,084 741 25,849 808 9,775 181 1993 4,799 41 5,152 58 5,039 46 4,419 34 1994 10,735 418 5,766 42 5,221 48 4,813 39 1995 3,639 28 3,788 37 8,252 88 7,733 49 1996 5,735 56 3,966 32 3,690 23 We also have some cumulative statistics for the Northridge aftershock sequence: All events 13,327 (190 of them this quarter) 3.0 - 3.9 389 (none this quarter) 4.0 - 4.9 50 (none this quarter) 5.0 and up 10 Here are similar numbers for the Landers/Big Bear aftershock sequenc: All events 64,599 (883 of them this quarter) 3.0 - 3.9 1,600 (8 of them this quarter) 4.0 - 4.9 167 (1 of them this quarter) 5.0 and up 22 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 ------------------------------------------------------------- 10/23 6:57 pm 32 26.9 118 8.1 2.2 28 mi. SSE of San Clemente Is. (SE tip) 10/24 12:37 pm 34 29.0 119 20.5 2.1 5 mi. WNW of Ojai 10/24 2:54 pm 34 28.8 119 21.6 2.0 6 mi. WNW of Ojai 10/24 8:34 pm 35 58.0 117 46.6 2.0 11 mi. ESE of Coso Junction 10/24 10:48 pm 34 28.8 119 21.8 3.5 6 mi. WNW of Ojai FELT 10/25 2:28 am 34 21.7 116 27.1 2.1 16 mi. N of Yucca Valley 10/25 2:37 am 34 9.5 116 25.7 2.4 2 mi. NNE of Yucca Valley 10/25 4:51 am 34 8.3 116 24.4 3.4 " 10/25 5:19 am 34 9.6 116 25.9 2.0 " 10/25 8:03 am 32 52.0 115 46.0 2.2 14 mi. SW of Westmorland 10/25 8:23 am 34 18.1 118 27.0 2.1 1 mi. NNW of San Fernando 10/25 10:27 am 35 43.2 118 4.5 2.3 23 mi. SSW of Coso Junction 10/25 2:39 pm 35 29.8 118 17.5 2.5 13 mi. SE of town of Lake Isabella 10/26 4:36 am 33 28.1 116 30.8 2.0 10 mi. ESE of Anza 10/26 9:15 am 33 46.8 116 8.3 2.0 6 mi. NE of Indio 10/26 1:31 pm 34 29.5 118 52.5 2.2 6 mi. NNE of Fillmore 10/26 4:42 pm 34 9.1 116 52.5 2.0 4 mi. NW of Mt. San Gorgonio 10/27 5:45 am 35 46.7 117 38.9 2.0 10 mi. N of Ridgecrest 10/28 2:41 am 33 28.0 116 28.8 2.1 12 mi. ESE of Anza 10/29 5:17 am 34 6.9 116 56.3 2.3 6 mi. W of Mt. San Gorgonio 10/29 8:16 am 34 37.5 116 36.0 2.4 23 mi. ENE of Lucerne Valley 10/29 8:30 am 33 0.1 115 34.4 2.8 3 mi. NW of Brawley 10/29 8:54 am 34 24.6 116 28.5 2.2 20 mi. N of Yucca Valley 10/29 10:02 am 34 17.7 118 27.6 2.6 1 mi. WNW of Pacoima 10/29 3:04 pm 35 4.5 116 41.5 2.1 22 mi. SSE of Goldstone Lake 10/29 4:46 pm 33 30.5 116 45.7 2.2 6 mi. WSW of Anza 10/30 6:56 am 35 49.0 116 14.2 2.3 11 mi. S of Shoshone 10/30 9:58 am 35 50.1 118 35.3 2.0 15 mi. NNW of town of Lake Isabella -------------------------------------------------------------