NEXT UPDATE: 9/10/05 (unless there is a significant increase in activity)
NOTE: This report focuses on a very small radius (20km) around Obsidian Butte and does not include the entire Brawley Seismic Zone.
CURRENT SWARM STATS:
Total Quakes (8/25 - 9/5 2:15am) = 626
dates
8/25 = 1 quake
8/26 = 0 quakes
8/27 = 0 quakes
8/28 = 8 quakes
8/29 = 15 quakes
8/30 = 2 quakes
8/31 = 220 quakes
9/1 = 251 quakes
9/2 = 80 quakes
9/3 = 34 quakes
9/4 = 11 quakes
9/5 = 4 quakes (preliminary)
These quake counts are likely to change with time as USGS officials manually review seismographs.
magnitudes
0.1 - 0.9 = 2 quakes
1.0 - 1.9 = 426 quakes
2.0 - 2.9 = 165 quakes
3.0 - 3.9 = 25 quakes
4.0 - 4.9 = 7 quakes
5.0+ = 1 quake
Obsidian Butte is one of several areas in California known for its earthquake swarms. Unlike The Geysers in Northern California and Coso Junction in Central California, Southern California's Obsidian Butte is sporadic and inconsistent with its swarming. While the other swarm areas rarely see days without quakes, Obsidian Butte can go months without registering a single quake. But when they come, they come in a big way. However, when the quakes do come, they come in volume and not strength.
Obsidian Butte is not known for producing large destructive quakes. Obsidian Butte has seen thousands and thousands of quakes over the years (nearly 10,000 since 1960). However, since 1900 there has only been a handful of quakes that have been stronger than a 5.0. The largest being a 5.8 in 1981. That was also the last time a 5.0 or larger quake was centered in the vicinity of Obsidian Butte.
HERE is a map
showing all 5.0+ quakes that have occurred near the Salton Sea since 1900. On the map you will notice that there are just a few quakes in the immediate area of Obsidian Butte. All Obsidian Butte swarms occur tight against the South-East shoreline of the Salton Sea.
This swarm is following a classic pattern. Reviewing past swarm data shows that this one is making a run to be one of the strongest in many years.
we have seen some impressive swarms since 1960. Here is a list of the most active months (minimum of 50 quakes):
APR 1981: 1250 quakes
SEP 2005: 380 quakes (preliminary)
AUG 2005: 285 quakes (preliminary)
MAR 1989: 248 quakes
NOV 1976: 239 quakes
MAY 1981: 184 quakes
JUN 1979: 169 quakes
NOV 1987: 162 quakes
JUL 1987: 152 quakes
MAY 1983: 130 quakes
OCT 1999: 112 quakes
MAY 1996: 107 quakes
OCT 1979: 105 quakes
JAN 1998: 94 quakes
APR 2003: 88 quakes
MAY 2000: 86 quakes
JUN 2000: 83 quakes
MAR 2004: 77 quakes
JUL 1983: 76 quakes
AUG 1996: 75 quakes
FEB 1989: 69 quakes
DEC 1997: 67 quakes
DEC 1988: 58 quakes
AUG 1986: 56 quakes
OCT 1988: 54 quakes
FEB 2002: 53 quakes
OCT 1995: 51 quakes
JUL 1992: 50 quakes
SEP 2003: 50 quakes
April 26, 1981 was most likely the most active day for swarm quakes at Obsidian Butte. 609 earthquakes were recorded on that day. This day also saw the strongest swarm related earthquake which was a 5.8.
Interestingly there has only been three, maybe four quakes above 5.0 at Obsidian Butte since 1900. We have already talked about the largest, a 5.8 on April 26, 1981. The others were a 5.1 on November 4, 1976 and a 5.5 on July 29, 1950.
The 5.1 in 1976 was also in the middle of a swarm. That particular swarm started at 04:57 with a 2.6 quake. The 5.1 occurred at 10:41 and was the 42nd quake to occur in the sequence. This 1976 swarm died out by the end of November with a total quake count of over 200.
Here is a list of all Obsidian Butte quakes with a magnitude of 4.0 or higher. There really isn't very many considering Obsidian Butte has been the host to nearly 10,000 earthquakes since 1960.
5.8 4/26/81
5.1 9/1/2005
5.1 11/4/76
4.7 10/16/99
4.6 8/31/2005
4.6 3/6/89
4.5 9/1/2005
4.5 8/31/2005
4.5 10/16/99
4.5 8/31/2005
4.4 8/31/2005
4.4 7/13/83
4.4 11/4/76
4.3 8/31/2005
4.2 11/4/76
4.2 11/4/76
4.2 10/27/63
4.2 10/19/88
4.1 8/31/2005
4.1 6/13/79
4.1 11/4/76
4.1 11/4/76
4.1 11/4/76
4.1 11/4/76
4.0 12/31/97
4.0 4/26/76
CURRENT SWARM REPORT
This report will be updated periodically to reflect new quakes. The map below (click for larger view) shows only quakes from this current swarm. These quakes will not be added to the main maps and lists until their magnitudes and locations have been reviewed and updated.
CURRENT OBSIDIAN QUAKES OF 3.0 AND GREATER
click here to see all quakes
3.7 9/5/2005 1:53 AM 1E Obsidian Butte, CA
3.0 9/3/2005 4:17 AM 1ENE Obsidian Butte, CA
3.4 9/1/2005 11:44 PM 1ENE Obsidian Butte, CA
3.3 9/1/2005 8:55 PM 3SSW Obsidian Butte, CA
3.3 9/1/2005 8:54 PM 2SSW Obsidian Butte, CA
3.1 9/1/2005 8:50 PM 1SW Obsidian Butte, CA
3.2 9/1/2005 8:46 PM 2SW Obsidian Butte, CA
3.7 9/1/2005 7:46 PM 1SSW Obsidian Butte, CA
3.0 9/1/2005 6:38 PM 1SSW Obsidian Butte, CA
3.8 9/1/2005 6:30 PM 2WSW Obsidian Butte, CA
5.1 9/1/2005 6:27 PM 1S Obsidian Butte, CA
4.5 9/1/2005 6:27 PM 0NE Obsidian Butte, CA
3.0 9/1/2005 6:23 PM 2E Obsidian Butte, CA
3.2 9/1/2005 7:06 AM 3NE Obsidian Butte, CA
4.4 9/1/2005 6:50 AM 1NNE Obsidian Butte, CA
3.6 9/1/2005 6:50 AM 0E Obsidian Butte, CA
3.5 9/1/2005 6:48 AM 1E Obsidian Butte, CA
3.1 9/1/2005 1:24 AM 1E Obsidian Butte, CA
3.1 8/31/2005 9:15 PM 1ENE Obsidian Butte, CA
4.5 8/31/2005 4:32 PM 3ENE Obsidian Butte, CA
3.4 8/31/2005 4:29 PM 2E Obsidian Butte, CA
4.3 8/31/2005 4:27 PM 3ENE Obsidian Butte, CA
4.1 8/31/2005 4:07 PM 1ENE Obsidian Butte, CA
3.1 8/31/2005 3:59 PM 0ESE Obsidian Butte, CA
3.2 8/31/2005 3:54 PM 1SSE Obsidian Butte, CA
4.5 8/31/2005 3:50 PM 2E Obsidian Butte, CA
4.6 8/31/2005 3:47 PM 1SSE Obsidian Butte, CA
3.5 8/31/2005 3:45 PM 1E Obsidian Butte, CA
3.1 8/31/2005 3:17 PM 1E Obsidian Butte, CA
3.1 8/31/2005 2:49 PM 1NE Obsidian Butte, CA
3.4 8/31/2005 9:18 AM 3ENE Obsidian Butte, CA
3.7 8/31/2005 8:35 AM 2NE Obsidian Butte, CA
3.1 8/29/2005 12:39 AM 4NE Obsidian Butte, CA
Here are some links to articles about the swarm:
Is there a relationship between the Salton Sea earthquake swarm near Obsidian Butte and the hurricane Katrina? (conscious junkyard)
Kate Hutton Earthquake commentary (SCSN)
SCSN Special Report (SCSN)
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