Seismo-Watch, Special Earthquake Report, Tehachapi Earthquake Swarm, January 2, 2003

Earthquake swarm hits the Tehachapi Mountains

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January 2, 2003

An earthquake swarm in Central California near Tehachapi increased this morning, producing two more quakes in the M 3.0 range, but there have been no reports of damage or injuries.

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According to the Southern California Seismic Network (SCSN), the earthquake swarm has been centered about 12 miles northeast of Arvin and 18 miles northwest of Tehachapi in the Tehachapi Mountains, near Caliente. See a Topozone topographic map or a MapQuest street map.

The swarm began on the 18th and continued with 1-5 quakes per day until Christmas Eve when it surged slightly, producing 10 quakes. Seven events were recorded on Christmas Day and the following two days were the quietest, producing a total of three event for the two days.

All of the activity up and until Christmas was relatively light, with largest events registering M 2.7. But then a few days later and on December 29, a M 3.1 happened and briefly kicked-started the sequence again, producing nine events that day. It was locally felt.

The series relaxed slightly in the following days, producing 4-7 quakes per day, however, another M 3.1 was detected on New Years Day.

The largest quakes of the swarm occurred this morning when at 8:11 and 8:15, two quakes registering M 3.6 shook the region. Both were felt from Tehachapi to Bakersfield, but there were no reports of items toppling from tables or shelves. Did you feel this quake? No damage has been reported and would not be expected for events of this magnitude.

More than 70 quakes have been recorded in the swarm thus far and it appears to be ongoing at the time of this report.

The focal depths suggest the action is rather shallow between 1-5 km deep, and most between 2-3 km deep.

Background
The activity appears to have occurred along the White Wolf fault zone, the same fault that caused the Arvin-Tehachapi (Kern County) M 7.5 earthquake in 1952. There are many small faults and fractures in this area, some of which trend northeast and parallel the White Wolf fault zone, but some that trend northwest and away from the White Wolf Fault. The White Wolf fault dips to the northwest and epicenters along the fault plane would plot on the northwest side of the fault. This recent activity was recorded slightly to the northwest of the main trace of the White Wolf Fault.

Additional seismic information links:

Mainstream media news reports:

Swarm of minor quakes hit Kern County - AP via San Francisco Chronicle