SCSN - The Southern California Seismic Network


Obsidian Butte Earthquake Swarm August-September, 2005 Above is a map showing the preliminary relocations of the ~300 earthquakes in the Obsidian Butte swarm. The Obsidian Butte Earthquake Swarm of August/September 2005 began on August 30th at 17:54 with a M1.4 earthquake, located 3km ENE of Obsidian Butte, CA. The seismicity appears to have migrated from southwest to the northeast in a short period of time, and is shallow - mostly in the depth range of 1 to 7 km. The SCSN moment tensors for the lager events that are also shown, exhibit mostly strike-slip faulting with a few cases of normal faulting. This region has had similar activity in the past, and this activity is usual for the Brawley seismic zone. These types of swarms can last for a few weeks and in some cases longer. The largest events, all larger than M4.0, occurred within 51 minutes of each other, and are listed below. To learn more about these events, stay tuned to SCSN.org. To read the SCSN Special Report, click here. Below is a list of M4+ events that have occurred during this swarm: 14178184 4.6 2005/08/31 15:47:44 33 9.6 N 115 37.8 W 0.0 1 km ( 1 mi) SSE of Obsidian Butte, CA 14178188 4.5 2005/08/31 15:50:24 33 10.4 N 115 36.7 W 2.0 2 km ( 2 mi) E of Obsidian Butte, CA 14178212 4.1 2005/08/31 16:07:16 33 10.5 N 115 37.1 W 4.6 2 km ( 1 mi) ENE of Obsidian Butte, CA 14178236 4.3 2005/08/31 16:27:32 33 11.4 N 115 35.1 W 2.2 5 km ( 3 mi) ENE of Obsidian Butte, CA 14178248 4.5 2005/08/31 16:32:11 33 11.1 N 115 35.8 W 3.7 4 km ( 3 mi) ENE of Obsidian Butte, CA

Obsidian Butte Earthquake Swarm

August-September, 2005

Above is a map showing the preliminary relocations of the ~300 earthquakes in the Obsidian Butte swarm.

The Obsidian Butte Earthquake Swarm of August/September 2005 began on August 30th at 17:54 with a M1.4 earthquake, located 3km ENE of Obsidian Butte, CA. The seismicity appears to have migrated from southwest to the northeast in a short period of time, and is shallow - mostly in the depth range of 1 to 7 km. The SCSN moment tensors for the lager events that are also shown, exhibit mostly strike-slip faulting with a few cases of normal faulting. This region has had similar activity in the past, and this activity is usual for the Brawley seismic zone. These types of swarms can last for a few weeks and in some cases longer. The largest events, all larger than M4.0, occurred within 51 minutes of each other, and are listed below. To learn more about these events, stay tuned to SCSN.org. To read the SCSN Special Report, click here.

Below is a list of M4+ events that have occurred during this swarm:

14178184 4.6 2005/08/31 15:47:44 33 9.6 N 115 37.8 W 0.0 1 km ( 1 mi) SSE of Obsidian Butte, CA
14178188 4.5 2005/08/31 15:50:24 33 10.4 N 115 36.7 W 2.0 2 km ( 2 mi) E of Obsidian Butte, CA
14178212 4.1 2005/08/31 16:07:16 33 10.5 N 115 37.1 W 4.6 2 km ( 1 mi) ENE of Obsidian Butte, CA
14178236 4.3 2005/08/31 16:27:32 33 11.4 N 115 35.1 W 2.2 5 km ( 3 mi) ENE of Obsidian Butte, CA
14178248 4.5 2005/08/31 16:32:11 33 11.1 N 115 35.8 W 3.7 4 km ( 3 mi) ENE of Obsidian Butte, CA


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