Rose Canyon fault poses biggest threat to San Diego, geologist says

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SAN DIEGO – The West Napa fault that triggered the 6.0 magnitude earthquake in Napa Valley Sunday is considered by experts a “sister fault” to the Rose Canyon in San Diego.

“They have similar rates, same sense of displacement and same distance out from the main San Andreas fault,” said Dr. Thomas Rockwell with San Diego State University.

According to the geology expert, both faults are capable of producing a magnitude 7.0 quake.

“The Rose Canyon fault is the fault that could hurt us the most,” Rockwell said.

San Diego earthquake fault line

Rose Canyon fault map

The Rose Canyon starts in La Jolla, runs through Mount Soledad, Rose Creek, down to the east side of Mission Bay and into Old Town and downtown San Diego.

“It’s a very populated area and very difficult to study because of that. The strongest shaking would be in San Diego itself before it dies out into the east county in terms of the strength of the shaking,” said Rockwell.

Rockwell explained that structures along the line that were built before the 1920s are likely to get more cracks, even collapse.

“The older houses that are on old ‘pier and post’ foundations can shift off the foundation during a strong earthquake,” said Rockwell.

One of the biggest threats from an earthquake is the risk of a fire – sparking from a broken gas line.

An automatic shut off valve, recommended by experts can cut the risk by shutting off the supply of gas to the home.

Another tip from experts is earthquake insurance, which doesn’t fall under typical homeowner’s insurance.

According to one San Diego insurance company, earthquake insurance can be offered with a 10 or 15% deductible rate and covers land movement and rebuild costs for a home.

Even though San Diego doesn’t have a history of major earthquakes, experts said quake activity since 1984 has doubled.

“There was an earthquake in San Diego on the Rose Canyon in 1862, it was close to the size of the Napa quake and it did a quite a bit of damage,” said Rockwell.