Santa Paula area trembles with
swarm of 10 mini-earthquakes in one day

September 23, 2015
Santa Paula News

The Santa Paula area was trembling Thursday with a series of 10 earthquakes reported ranging from a miniscule 1.4 magnitude to a stronger 2.8 magnitude according to the U.S. Geological Survey.

And then the Fillmore swarm started moving again with nine minor seismic episodes reported September 19.

Santa Paula’s largest micro-earthquake — 2.8 magnitude — was recorded Thursday, September 17 at 2:43 p.m. seven miles north of Santa Paula and nine miles west-northwest of Fillmore.

The exact location was reported as 34.453N 119.053W at a depth of 10 miles. Those living in the area reported feeling a “jolt” but there was no damage reported from the minor event.

The September 17 Santa Paula swarm started at 11:30 a.m. with a 1.6 magnitude event eight miles north of the city; that initial mini-shaker was rapidly followed by a 1.7 magnitude at 11:40 a.m. seven miles north of Santa Paula. All the seismic events ping ponged between six and eight miles north of the city with the 2.8 magnitude event followed by higher readings of two 1.9 magnitude shakers as well as smaller movements.

There had been a 1.3 magnitude event September 13 eight miles north of Santa Paula.

In July there was an earthquake swarm in the Santa Clara River Valley of more than 200 small shakers.

Known officially as the Fillmore Swarm, seismologists reported the bulk of the shakers were four to five miles west of Fillmore, which put the activity four to five miles east of Santa Paula.

According to a special report on the activity, the July cluster had been occurring very near to or directly under the Toland Road Landfill, just where opponents to the landfill expansion  in the mid-1990s said they feared an active fault was located.

The swarm was addressed in a special report by the Southern California Seismic Network (SCSN) “consists of a number of clusters” the most intense activity peaking on July 9 with 10 to 13 seismic events per hour. And the activity was about halfway between the San Cayetano Fault to the north and the Oak Ridge Fault to the south.

The SCSN had not recorded a similar swarm in Ventura County since 1981 and considered the seismic event “very unusual” in light of the lack of larger magnitude 3 or above events that could be expected during such a swarm.  

 The Southern California Seismic Network is the clearinghouse of all things earthquakes and includes Caltech and USGS among other agencies.

To read the SCSN report on the July Santa Clara River Valley swarm visit:

www.scsndev.gps.caltech.edu/index.php/earthquakes/speqrep/20150709-m2-8-fillmore-swarm.





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