Scientist Calls for Seismic Safety Study : Earthquakes: It’s not known whether a reported fault zone stretching from Thousand Oaks to Camarillo is active.

The former state geologist who believes he has detected an earthquake fault zone running alongside the Ventura Freeway, through Thousand Oaks and into Camarillo, said Thursday that further study should be undertaken soon to determine the area’s seismic safety.

“We have no idea if it’s active or inactive, but if it’s active it could bring about slight modifications in structural designs,” geologist James Slosson said. “We’re not saying the world is coming to an end. It’s just something that has to be studied.”

The news caught some local geologists off guard.

“All this stuff is speculation,” county geologist Jim Fisher said. “It’s not alarming, that’s for sure. I don’t think any of these faults have ruptured in the last 10,000 or 11,000 years.”

Fisher said he would welcome further study on the suspected fault zone.

“We have so many active faults in the county, but we don’t have any active faults in the Thousand Oaks area,” he said. “If it were found, in the future, to be active, this would definitely be a major change in our understanding of seismic hazard in Thousand Oaks.”

Seismologists have identified five major active faults and many smaller active faults snaking through the county. Despite continuing geological movement along these faults, the county historically has had few significant earthquakes.

Fisher said the Long Grade Canyon Fault has already been found running between the Potrero Valley area near Newbury Park, to Camarillo State Hospital. He also suspects that another fault runs along California 23.

Slosson announced the potential of a new fault zone at a regional meeting of the Geological Society of America in Reno on Wednesday. He said he suspected he has located a fault zone based on certain rock formations and other topographical features.

“From Calabasas to Camarillo there are a series of small little hills which are at an angle and are disoriented with the Simi hill structure,” he said Thursday. “There’s also a line of springs and highly disturbed faulted rocks in that area.”

Slosson said a series of artesian springs and hot springs in the Thousand Oaks area also suggest the presence of earthquake faults.

“It’s a zone of fractured rock that has an east-west alignment,” he said. “We’re not saying this is an active fault, but the rock material in the area is highly disturbed.”

Thomas Blake, an engineering geologist with the Ventura consulting firm Fugro-McClelland, said the alignment of vegetation and drainage against the south side of the mountains in Newbury Park might suggest seismic activity.

“I’m considering it potentially active,” he said. In scientific terms, potentially active faults are those that have erupted between 10,000 and 2 million or 3 million years ago. “We don’t have unequivocal information,” he said.

The entire 30-mile zone, named by Slosson the South San Fernando Fault, runs alongside the Ventura Freeway from the eastern tip of Camarillo into Los Angeles, Slosson said.

California Department of Transportation spokesman Jim Drago said he would like to know more about the fault zone’s proximity to the freeway.

“This is something we’re certainly interested in. What type of a fault is it? Is it active? What are the particulars,” he said. “As we get more and more information on earthquake faults, we’re looking to the scientific community for how we factor in strengthening techniques and retrofitting.”

Geologists agree that Ventura County, particularly north and west of the Santa Clara River, is one of the more seismically active areas in the state.

This is because the Pacific Plate, a large coastal land mass floating on the earth’s core, is moving north-south, while the San Andreas Fault, in an area near the county, is moving into it in an east-west path.