October 21, 1993 Weekly Earthquake Report for Southern California ------------------------------------------------ October 14 - October 20, 1993 Prepared by: Kate Hutton, Seismological Laboratory (kate@bombay.gps.caltech.edu) Lucy Jones, U.S. Geological Survey California Institute of Technology This document is a commentary on current seismic activity. The earthquakes discussed have been detected and processed automatically. All epicenters and magnitudes have been reviewed to exclude obvious blunders; however, they must still be considered preliminary. 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, October 14, Pacific Daylight Time, to midnight Wednesday night, October 20, Pacific Daylight Time. The map includes a virtually complete set of earthquakes of M2.0 or larger, plus many smaller ones that happen to have made it through the data processing. There are 380 this time. The largest events this week were both M3.2. The first of these occurred early Sunday morning in the northeastern Mojave Desert. It occurred about 40 km to the east of the Landers aftershock zone, so probably was not an aftershock. The other, definitely a Landers aftershock, occurred near Yucca Valley on Monday evening. This latter one was felt. Another interesting quake occurred at 2:49 pm on Monday. It was M4.6, but occurred just south of the edge of the map, 117 miles WSW of San Diego. It was not felt. However, our as-yet-imperfect automatic system located it at Huntington Beach, and it was mistakenly reported to the press that way. We do sometimes make mistakes. It turns out that "regional" earthquakes, ie. those just outside of the network, are a major challenge for automatic reporting systems. The table lists the quakes that were M2.0 or larger in the central part of the coverage area. Only M2.5 and larger events are listed for south of the U.S./Mexico border, and for the Coalinga/Parkfield area. For more information on the latter, see the Northern California Report issued by the U.S.G.S. in Menlo Park. Times are local times; if you want Greenwich Mean Time, add 7 hrs. to the Pacific Daylight Time listed. Table 1 ------- Date Time N Lat. W Long. Mag ------------------------------------------------------------- 10/14 12:25 am 32 22.6 115 3.7 2.9 32 mi. SE of Calexico 10/14 2:22 am 32 24.9 115 3.1 2.5 " 10/14 2:37 am 35 0.1 116 57.6 2.0 8 mi. NNE of Barstow 10/14 2:37 am 35 0.0 116 57.5 2.0 " 10/14 3:13 am 35 9.2 119 13.6 2.4 12 mi. E of Taft 10/14 8:00 am 34 21.3 116 27.6 2.4 16 mi. N of Yucca Valley 10/14 1:15 pm 35 0.3 116 54.2 2.8 10 mi. NE of Barstow; FELT 10/14 3:22 pm 32 22.6 115 3.7 2.6 32 mi. SE of Calexico 10/14 5:13 pm 32 22.5 115 3.5 2.6 " 10/14 7:54 pm 32 23.3 115 3.7 2.9 " 10/15 5:14 am 34 57.3 120 43.4 2.0 16 mi. W of Santa Maria 10/15 8:29 am 35 13.0 117 23.5 2.4 31 mi. SSE of Ridgecrest 10/15 10:25 am 34 1.7 116 19.8 2.5 9 mi. SE of Yucca Valley 10/15 11:57 am 34 14.5 116 25.5 3.0 8 mi. N of Yucca Valley FELT 10/15 12:15 pm 34 14.8 116 25.4 2.6 " 10/15 1:22 pm 35 0.6 116 58.5 2.2 8 mi. NNE of Barstow 10/15 1:54 pm 34 36.3 116 40.2 2.2 19 mi. NE of Lucerne Valley 10/15 6:57 pm 34 21.3 116 28.1 2.0 16 mi. N of Yucca Valley 10/16 6:43 am 36 2.1 117 49.2 2.3 7 mi. E of Coso Junction 10/16 6:46 am 36 2.0 117 49.4 2.0 " 10/16 8:11 pm 34 10.4 116 25.8 2.6 3 mi. NNE of Yucca Valley 10/16 8:11 pm 36 7.4 120 4.9 2.6 15 mi. E of Coalinga 10/17 2:58 am 33 41.9 116 43.3 2.1 3 mi. S of Idyllwild 10/17 4:32 am 34 8.2 116 47.0 2.9 3 mi. NE of Mt. San Gorgonio 10/17 4:43 am 35 8.9 116 34.1 3.2 22 mi. SE of Goldstone (dry) Lake 10/17 5:19 am 35 8.1 116 34.5 2.1 " 10/17 5:48 am 34 22.7 116 27.6 2.3 17 mi. N of Yucca Valley 10/17 6:30 am 34 34.1 116 34.6 2.0 22 mi. ENE of Lucerne Valley 10/17 2:06 pm 34 32.5 116 30.2 2.4 29 mi. N of Yucca Valley 10/17 3:30 pm 34 59.5 116 57.0 2.4 8 mi. NNE of Barstow 10/17 5:28 pm 32 10.3 116 40.4 2.8 33 mi. SE of San Ysidro 10/18 4:37 am 35 13.3 119 33.2 2.4 8 mi. NW of Taft 10/18 4:42 am 34 14.3 116 26.5 2.3 8 mi. N of Yucca Valley 10/18 5:05 am 32 22.1 115 3.3 2.5 33 mi. SE of Calexico 10/18 6:57 am 34 29.3 116 31.2 2.1 25 mi. N of Yucca Valley 10/18 8:04 am 33 37.7 119 2.9 2.1 10 mi. N of Santa Barbara Is. 10/18 9:03 am 34 48.7 120 59.3 2.7 25 mi. NW of Pt. Arguello 10/18 12:49 pm 36 10.2 120 4.5 2.7 16 mi. E of Coalinga 10/18 7:40 pm 34 11.9 116 25.9 3.2 5 mi. N of Yucca Valley FELT 10/18 8:13 pm 34 13.9 116 26.4 2.5 7 mi. N of Yucca Valley 10/18 10:17 pm 35 34.2 118 25.2 2.1 5 mi. SSE of the town of Lake Isabella 10/19 1:13 am 33 59.7 116 18.2 2.2 11 mi. SE of Yucca Valley 10/19 1:36 pm 34 23.7 116 27.9 2.3 19 mi. N of Yucca Valley 10/19 1:37 pm 34 23.6 116 27.8 2.8 " 10/19 2:39 pm 35 53.3 116 44.7 2.0 27 mi. SE of Telescope Peak, Panamint Range 10/19 3:59 pm 36 10.3 118 15.0 2.2 15 mi. WSW of Olancha 10/19 6:55 pm 34 55.7 116 55.7 2.3 6 mi. ENE of Barstow 10/19 9:27 pm 34 23.6 116 27.8 2.3 19 mi. N of Yucca Valley 10/19 10:18 pm 33 43.9 118 1.7 2.1 4 mi. E of Seal Beach 10/19 11:50 pm 35 17.4 118 32.0 2.8 12 mi. NNW of Tehachapi 10/20 5:56 am 33 53.3 116 44.6 2.1 3 mi. SE of Cabazon 10/20 6:48 am 35 39.4 119 19.0 2.9 24 mi. NW of downtown Bakersfield 10/20 9:19 am 32 24.8 115 3.2 2.5 31 mi. SE of Calexico 10/20 10:14 am 34 0.5 116 19.2 2.6 10 mi. SE of Yucca Valley 10/20 12:08 pm 36 9.2 118 2.1 2.7 5 mi. WNW of south end of Haiwee Reservoir 10/20 12:35 pm 36 10.1 118 1.5 2.1 " 10/20 3:50 pm 34 6.1 116 59.8 2.0 9 mi. SE of Running Springs 10/20 3:59 pm 34 9.4 116 24.2 2.0 3 mi. NE of Yucca Valley 10/20 4:09 pm 34 26.6 116 29.5 2.3 22 mi. N of Yucca Valley 10/20 9:58 pm 36 18.1 120 20.1 2.8 11 mi. N of Coalinga ------------------------------------------------------------- Figure. A map of southern California showing the earthquakes recorded during the past week by the Caltech/USGS Seismic Network. Major faults are marked, as well as the metropolitan areas of Los Angeles (L.A.), Palm Springs (P.S.), San Diego (S.D.), and Santa Barbara (S.B.). The circles denote the earthquakes, the size of the circle indicating the magnitude.