SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey June 22, 1995 Weekly Earthquake Report for Southern California ------------------------------------------------ June 15 - 21, 1995 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 818-395-6326. For daily updates, call our Earthquake Information Hotline: 818-395-6977. -------------------------------- This week's Report covers the time period from midnight Thursday morning, June 15, Pacific Daylight Time, to midnight Wednesday night, June 21, 1995, Pacific Daylight Time. We recorded 299 earthquakes of M1.0 or larger during the 7-day period covered. The largest quake of the week occurred yesterday (Wednesday) afternoon, at 2:17 pm; it was a M4.1 located offshore of the San Clemente/Oceanside area. It was fairly widely felt in the coastal areas from San Diego to Orange County, but was too weak to cause any damage. The focal mechanism was thrust. This quake occurred near the famous Oceanside aftershock sequence, which followed the July 13, 1986 Mw5.4 event. The sequence was notworthy because, even though the mainshock was only Mw5.4, there were close to 3,000 aftershocks over the next six years. We have not seen much activity there in the last few years, however, so we refrain from calling this week's quake an Oceanside aftershock. Our current aftershock sequences, namely Landers/Big Bear and Northridge, produces a handful of quakes of feelable size this week. The Landers sequence produced a M3.0 early Friday evening, which was felt, a M3.2 just after midnight Saturday, and a M3.5 near Barstow early Monday morning. The last was felt. These all has strike-slip mechanisms, as have most of the Landers quakes. There was another Barstow quake, M2.9, in the wee hours of the morning yesterday. The Northridge sequence produced a M3.0 early Monday morning, in the San Fernando area. It was felt. There was also a M3.0 in the Coso Range, near Ridgecrest, around noon on Sunday. A very small quake (M2.1) was apparently felt southeast of Ontario early Friday afternoon. This general vicinity has had a large number of small quakes in the past few years, many of which have been felt simply because they occurred at a shallower depth than most of the quakes in our region do. Friday's quake occurred at a depth of 2.6 km. 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 ------------------------------------------------------------- 6/15 5:54 am 34 9.6 116 26.5 2.2 2 mi. N of Yucca Valley 6/15 9:46 am 34 23.4 116 28.0 2.4 18 mi. N of Yucca Valley 6/15 9:56 am 35 8.0 118 57.6 2.0 7 mi. N of the I5/99 interchange 6/15 2:29 pm 33 56.1 116 21.5 2.1 8 mi. ESE of Desert Hot Springs 6/16 4:55 am 34 56.4 116 53.5 2.0 8 mi. ENE of Barstow 6/16 4:57 am 34 56.2 116 54.0 2.0 7 mi. ENE of Barstow 6/16 6:34 am 34 31.5 116 31.1 2.2 28 mi. N of Yucca Valley 6/16 6:44 am 34 7.2 116 59.5 2.3 8 mi. SE of Running Springs 6/16 7:28 am 34 13.9 118 39.5 2.0 3 mi. NW of Canoga Park 6/16 12:25 pm 34 2.5 118 45.7 2.3 3 mi. NE of Pt. Dume 6/16 12:47 pm 34 1.8 117 30.8 2.1 2 mi. E of the I60/I15 interchange; FELT? 6/16 2:58 pm 34 8.6 116 25.9 2.1 1 mi. NNE of Yucca Valley 6/16 6:21 pm 34 21.1 116 28.1 3.0 16 mi. N of Yucca Valley FELT 6/16 10:52 pm 33 10.8 116 1.6 2.6 6 mi. ENE of Ocotillo Wells 6/16 11:29 pm 34 9.9 116 27.0 2.0 3 mi. N of Yucca Valley 6/17 12:56 am 34 39.0 116 39.5 3.2 21 mi. NE of Lucerne Valley 6/17 5:29 am 34 16.6 118 28.1 3.0 1 mi. WSW of San Fernando FELT 6/17 7:50 am 35 0.8 116 58.7 2.0 8 mi. NNE of Barstow 6/18 3:35 am 34 26.2 116 27.2 2.0 22 mi. N of Yucca Valley 6/18 12:28 pm 36 0.5 117 49.0 3.0 7 mi. ESE of Coso Junction 6/18 12:30 pm 36 6.8 119 56.7 2.9 23 mi. E of Coalinga 6/18 1:24 pm 36 5.1 117 54.2 2.1 3 mi. NE of Coso Junction 6/18 5:51 pm 34 6.8 116 23.6 2.0 3 mi. E of Yucca Valley 6/18 7:56 pm 32 39.8 115 41.2 2.1 11 mi. SW of El Centro 6/18 11:20 pm 34 11.1 116 26.5 2.1 4 mi. N of Yucca Valley 6/19 1:00 am 34 5.9 116 60.0 2.3 9 mi. SE of Running Springs 6/19 3:40 am 34 56.5 116 53.1 3.5 8 mi. ENE of Barstow FELT 6/19 4:51 am 34 56.3 116 53.1 2.4 " 6/19 10:26 am 32 37.5 115 47.7 2.0 13 mi. ESE of Ocotillo 6/19 10:47 am 36 0.4 117 48.8 2.1 7 mi. ESE of Coso Junction 6/19 4:40 pm 34 20.0 118 42.5 2.6 3 mi. N of Simi Valley 6/19 4:51 pm 34 7.2 116 51.9 2.2 2 mi. WNW of Mt. San Gorgonio 6/19 5:17 pm 34 56.6 116 53.0 2.2 8 mi. ENE of Barstow 6/19 5:26 pm 35 53.2 118 2.6 2.0 12 mi. SSW of Coso Junction 6/20 1:31 am 34 20.4 116 38.2 2.4 13 mi. ENE of Big Bear City 6/20 5:07 am 35 37.7 119 52.5 2.0 20 mi. NNE of Simmler 6/20 3:20 pm 34 12.0 116 51.9 2.2 3 mi. SE of town of Big Bear Lake 6/20 3:53 pm 34 13.5 118 25.5 2.0 3 mi. S of San Fernando 6/20 10:53 pm 33 58.7 118 26.5 2.2 Under Marina del Rey 6/20 11:40 pm 34 2.7 117 16.0 2.4 Under Loma Linda 6/21 1:06 am 34 56.4 116 53.0 2.9 8 mi. ENE of Barstow 6/21 2:17 pm 32 59.1 117 49.0 4.1 32 mi. SSW of San Clemente FELT 6/21 6:54 pm 33 54.0 116 17.8 2.0 13 mi. NNE of Palm Desert 6/21 7:24 pm 34 3.2 116 23.5 2.3 5 mi. SE of Yucca Valley 6/21 8:48 pm 34 17.7 118 36.6 2.0 6 mi. N of Canoga Park 6/21 10:19 pm 35 2.5 116 59.7 2.1 10 mi. N of Barstow -------------------------------------------------------------