July 14, 1994 Weekly Earthquake Report for Southern California ------------------------------------------------ July 7 - 13, 1994 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, July 7, Pacific Daylight Time, to midnight Wednesday night, July 13, Pacific Daylight Time. We recorded 320 earthquakes this week. The largest event of the week was a M3.7 near Simi Valley late Sunday night, which occurred about one minute after a M3.3 at the same location. Both were Northridge aftershocks. Several other Northridge aftershocks were also felt, including a M3.1 last Thursday morning, a M2.8 on Friday, a M3.0 on Saturday, and a M2.7 on Monday morning. Four M3 or larger aftershocks is a little bit higher than the expected number, which at this point in the sequence is one or two per week. However, we've had plenty of weeks that were lower than expected. That's statistical fluctuation for you. The table lists the quakes 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 Daylight Time listed. Table 1 ------- Date Time N Lat. W Long. Mag ------------------------------------------------------------- 7/7 6:21 am 34 57.1 116 55.5 3.0 7 mi. NE of Barstow 7/7 7:07 am 34 23.9 118 40.5 2.0 5 mi. WSW of Magic Mtn. 7/7 7:22 am 34 1.2 116 21.0 2.1 8 mi. SE of Yucca Valley 7/7 8:19 am 34 17.1 118 27.1 3.1 Under San Fernando; FELT 7/7 8:46 am 34 57.0 116 55.6 3.0 6 mi. NE of Barstow 7/7 12:00 pm 34 28.5 116 30.1 2.0 24 mi. N of Yucca Valley 7/7 12:18 pm 34 34.3 116 31.0 2.0 25 mi. ENE of Lucerne Valley 7/7 2:22 pm 34 24.0 116 28.1 2.0 19 mi. N of Yucca Valley 7/8 1:40 am 34 19.0 118 25.0 2.0 2 mi. NNE of San Fernando 7/8 8:15 am 34 1.0 117 6.5 2.2 4 mi. SE of Redlands 7/8 10:30 am 36 15.1 120 15.4 2.6 9 mi. NE of Coalinga 7/8 11:44 am 34 16.1 118 36.7 2.8 4 mi. N of Canoga Park; FELT 7/8 12:52 pm 34 20.5 116 27.4 2.1 15 mi. N of Yucca Valley 7/8 3:45 pm 35 45.6 118 22.1 2.2 10 mi. NNE of the town of Lake Isabella 7/8 10:28 pm 34 17.5 118 27.2 2.2 1 mi. NW of San Fernando 7/8 10:49 pm 35 41.8 117 16.1 2.0 7 mi. SE of Trona 7/9 6:49 am 34 14.8 118 29.2 2.0 2 mi. ENE of Northridge 7/9 8:36 am 36 5.1 117 52.4 2.0 5 mi. NE of Coso Junction 7/9 1:47 pm 34 15.1 118 30.0 2.2 2 mi. ENE of Northridge 7/9 3:56 pm 34 17.4 118 27.0 3.0 Under San Fernando; FELT 7/9 11:15 pm 34 34.6 116 36.3 2.1 21 mi. ENE of Lucerne Valley 7/9 11:21 pm 34 37.2 116 35.6 2.1 23 mi. ENE of Lucerne Valley 7/9 11:36 pm 34 2.2 116 21.6 2.0 7 mi. SE of Yucca Valley 7/10 1:02 am 35 37.2 115 55.2 2.4 26 mi. NNE of Baker 7/10 8:09 am 35 17.9 118 34.8 2.1 13 mi. NNW of Tehachapi 7/10 12:06 pm 34 47.5 116 17.6 2.8 34 mi. SSW of Baker 7/10 12:07 pm 34 46.9 116 18.8 2.7 " 7/10 5:40 pm 35 27.3 118 54.7 2.9 7 mi. NE of downtown Bakersfield 7/10 10:52 pm 34 9.2 116 25.7 2.3 2 mi. NNE of Yucca Valley 7/10 11:49 pm 34 15.4 118 41.5 3.3 1 mi. SS of Simi Valley; FELT 7/10 11:50 pm 34 15.6 118 41.5 3.7 " FELT 7/11 2:30 am 32 0.7 114 57.4 3.1 51 mi. SSW of Yuma, Arizona 7/11 3:54 am 36 0.4 117 48.5 2.0 8 mi. ESE of Coso Junction 7/11 6:35 am 34 23.8 116 27.3 2.3 19 mi. N of Yucca Valley 7/11 7:11 am 34 22.5 116 27.9 2.3 17 mi. N of Yucca Valley 7/11 7:34 am 34 37.8 116 36.6 3.1 23 mi. NE of Lucerne Valley 7/11 7:48 am 34 37.6 116 36.8 2.2 " 7/11 8:27 am 33 50.4 118 16.0 2.5 1 mi. SE of the I110/I405 interchange, Carson 7/11 8:37 am 34 15.6 118 41.8 2.7 1 mi. SSE of Simi Valley; FELT 7/11 10:06 am 34 47.3 116 17.7 2.8 35 mi. SSW of Baker 7/12 12:06 am 34 22.3 119 28.4 2.1 3 mi. ESE of Carpinteria 7/12 4:08 am 35 0.8 119 10.0 2.5 12 mi. W of the I5/99 inter- change 7/12 2:58 pm 34 23.9 116 28.0 2.1 19 mi. N of Yucca Valley 7/12 3:49 pm 34 5.6 116 22.7 2.4 4 mi. ESE of Yucca Valley 7/12 5:45 pm 33 50.2 117 43.8 2.2 5 mi. SE of Yorba Linda 7/12 8:02 pm 34 33.8 116 26.9 2.0 30 mi. N of Yucca Valley 7/12 8:22 pm 32 20.4 118 52.6 2.8 45 mi. SW of San Clemente Is. 7/12 9:59 pm 33 18.5 115 42.3 2.6 3 mi. SSE of Bombay Beach 7/12 10:30 pm 32 34.3 117 18.1 2.0 13 mi. SSW of the I5/I8 interch., San Diego 7/13 11:02 am 34 20.6 116 28.0 2.2 15 mi. N of Yucca Valley 7/13 1:55 pm 34 16.1 116 27.4 2.4 10 mi. N of Yucca Valley ------------------------------------------------------------- Figure 1. 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.