Swarm of small quakes rattles Fillmore area of Ventura County

LOS ANGELES - A swarm of nearly 30 small earthquakes have struck near the Ventura County community of Fillmore since last week, but seismologists said the rash of temblors is unlikely to trigger a larger shock.

All the quakes registered less than magnitude 3.0, too small to be felt by most people or to cause any damage.

''It's not every day that we have things like this and it's a higher level than a normal swarm, but I don't read any particular significance into it,'' Lucy Jones, scientist in charge of the U.S. Geological Survey's Pasadena office, said Tuesday.

The swarm is in the vicinity of the Oak Ridge Fault system, which runs more than 50 miles from Piru to southeast of Ventura. Some seismologists believe that the deadly 1997 Northridge earthquake was triggered on the system's southern end.

Series of similarly sized quakes rarely lead up to anything bigger, Jones said.

''Once you have a swarm going, you're more likely to trigger others,'' she said. ''But you're most likely to trigger it immediately and within the magnitude (of previous quakes). ... If anything, it shows you have lots of little ones so you don't get the big one.''

Fillmore, about 70 miles northwest of downtown Los Angeles, was Ventura County's hardest-hit area in the Northridge quake. Officials reported 40 minor injuries and $200 million in damage, including the collapse of the landmark Fillmore Hotel.

A swarm of small quakes in Santa Monica Bay preceded the Northridge quake, but scientists believe it was coincidental.

Another series of quakes is rattling the Obsidian Butte area southeast of the Salton Sea. That swarm has produced three magnitude-3.0 quakes and higher since June 6 and has been occurring for the past 11 years, Jones said.

On the Net: Earthquakes in California: http://pasadena.wr.usgs.gov/recenteqs/