The time period covered is 5 pm on Thursday, September 24, 2004 (PDT)
through 5 pm on Thursday,
September 30, 2004 (PDT). During this period
we dectected and analyzed 300 earthquakes. Click
here to see a map.
The table below lists the quakes during the past 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.
Mag. PDT Date PDT Time Lat. Long. Depth Descriptive location
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#EVID MAG YYYY/MM/DD HH:mm:SS LAT LON DEP LOCATION
14094104 2.1 2004/09/24 14:37:36 36 17.2 N 118 1.4 W 5.6 2 km ( 1 mi) WNW of Olancha, CA
14094252 2.3 2004/09/25 03:29:13 33 11.2 N 115 36.5 W 3.4 3 km ( 2 mi) NE of Obsidian Butte, CA
14094580 2.1 2004/09/26 16:57:55 33 57.9 N 116 55.1 W 17.9 6 km ( 4 mi) NW of Banning, CA
14094632 2.4 2004/09/27 02:31:19 35 33.5 N 118 28.4 W 1.9 9 km ( 5 mi) S of town of Lake Isabella, CA
14094652 2.4 2004/09/27 06:05:20 32 3.5 N 115 50.3 W 6.0 75 km (47 mi) SSW of Calexico, CA
14094664 2.1 2004/09/27 07:43:18 32 27.8 N 115 19.8 W 6.0 28 km (17 mi) SE of Calexico, CA
14094676 2.2 2004/09/27 08:21:55 34 9.7 N 117 19.9 W 12.0 7 km ( 4 mi) NNW of San Bernardino, CA
14094696 2.2 2004/09/27 09:44:57 34 23.1 N 116 54.5 W 11.1 7 km ( 5 mi) SSE of Lucerne Valley, CA
14094708 2.6 2004/09/27 11:48:04 32 29.8 N 116 16.7 W 13.5 38 km (23 mi) SW of Ocotillo, CA
14095172 2.9 2004/09/28 15:07:51 32 9.2 N 115 50.6 W 7.0 66 km (41 mi) SSW of Calexico, CA
14095420 2.5 2004/09/29 03:22:19 32 56.8 N 116 30.6 W 8.2 17 km (10 mi) SSE of Julian, CA
14095588 2.3 2004/09/29 12:32:54 32 1.9 N 115 20.8 W 6.0 72 km (45 mi) S of Calexico, CA
Wednesday, September 29 10:10AM local time
The Mw6.0 event in Parkfield, CA was not within the SCSN network, but felt throughout Southern California. To see the
ShakeMap for the Parkfield Earthquake, click here.
To see a map of the "felt" locations, or if you felt this quake and would like to report it,click here.
To read the PARKFIELD EARTHQUAKE SPECIAL REPORT, click here.
14095628 5.0 2004/09/29 15:54:54 35 23.4 N 118 37.4 W 3.5 28 km (17 mi) NE of Arvin, CA
This Mw5.0 mainshock for the Arvin earthquake was not a Parkfield aftershock, but a new quake. This quake was felt
as far away as Sacramento to the north, Las Vegas to the east, and Redlands to the south.
To see the ShakeMap for this event, click here.
To see a map of the "felt" locations, or if you felt this quake and would like to report it,click here.
To read the ARVIN EARTHQUAKE SPECIAL REPORT, click here.
14095648 2.1 2004/09/29 16:07:25 35 23.4 N 118 38.0 W 5.6 27 km (17 mi) NE of Arvin, CA
14095664 2.6 2004/09/29 16:11:27 32 6.6 N 116 25.2 W 6.0 76 km (48 mi) SE of San Ysidro, CA
14095672 2.4 2004/09/29 16:21:56 35 23.8 N 118 37.8 W 5.6 28 km (17 mi) NE of Arvin, CA
14095684 2.3 2004/09/29 16:25:41 35 24.4 N 118 37.9 W 5.6 28 km (18 mi) NE of Arvin, CA
14095736 2.0 2004/09/29 17:11:00 35 23.1 N 118 38.1 W 5.6 27 km (16 mi) NE of Arvin, CA
14095852 2.5 2004/09/29 20:30:47 34 29.3 N 116 15.4 W 4.5 39 km (24 mi) N of Joshua Tree, CA
14095856 2.8 2004/09/29 20:56:53 35 23.0 N 118 37.6 W 5.6 27 km (17 mi) NE of Arvin, CA
14095976 2.5 2004/09/30 01:24:58 35 23.7 N 118 37.8 W 5.6 28 km (17 mi) NE of Arvin, CA
14096000 2.1 2004/09/30 01:47:57 35 23.3 N 118 37.5 W 5.6 27 km (17 mi) NE of Arvin, CA
14096008 2.5 2004/09/30 02:29:25 34 13.9 N 118 23.8 W 11.2 5 km ( 3 mi) ENE of Panorama City, CA
Possibly felt in Panorama City. If you felt this quake, and would like to report it, click here.
14096044 2.4 2004/09/30 04:53:17 35 24.4 N 118 37.7 W 5.6 29 km (18 mi) NE of Arvin, CA
14096048 2.2 2004/09/30 04:57:46 35 24.0 N 118 38.3 W 5.6 28 km (17 mi) NE of Arvin, CA
### Number of rows returned:25
If you any earthquake, and would like to report it, click here.
Please email questions and comments to Anthony Guarino at:
AGuarino@gps.caltech.edu
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Commentary
2004 ARVIN EARTHQUAKE SUMMARY
A Mw5.0 earthquake occurred in southern California on Wednesday, Sept. 29 at 3:54 p.m. located 17 miles northeast of Arvin in the southern Sierra Nevada. Because this occurred just over a day and less than 200 km southeast of the Mw6.0 Parkfield earthquake, there may be a correlation between the events. We have in the past, such as July 1986 and June-July 1992, seen multiple occurrences of moderate to large earthquakes over wide areas of California.
The proximity of these two earthquakes in time and space, while not completely understood, is consistent with our growing understanding that earthquakes can sometimes be triggered by other earthquakes. Because investigations of triggered earthquakes remain in their infancy, we cannot quantify precise probabilities of further triggered events beyond saying “very low.” The precise nature of the relationship (if any) between the two earthquakes is also unclear, and may be illuminated by future in-depth analysis of the data. As with any M5.0 earthquake, however, the Mw5.0 mainshock has begun generating its own local aftershocks.
The Mw5.0 had a strike-slip focal mechanism, with left-lateral motion on a nodal plane striking N65W. This is opposite motion to what is normally observed for San Andreas type earthquakes. The depth of the event is about 6.5 km.
These earthquakes accommodate crustal thinning within the southern Sierra Nevada. Extension occurs in both north-south and east-west direction, causing gradual oblate flattening of the range. The extensional deformation is associated with areas of high potential energy, and may be seismic expression of buoyancy-driven thinning of the Sierran lithosphere.
This earthquake today occurred about 8 km to the north of a M4.3 earthquake that occurred 25 January 2003. The 2003 M4.3 event was part of a large swarm of earthquakes that consisted of more than 1000 smaller events.