A magnitude 6.9 earthquake on San Diego's Rose Canyon Fault could damage 100,000 homes, cause widespread road and bridge failures and make parts of Mission Bay sink about a foot, according to a newly released report.
The report, by the San Diego chapter of the Earthquake Engineering Research Institute (EERI), found that such a temblor could also cut gas and water service between La Jolla and the Silver Strand for months, collapse key municipal buildings and close the San Diego-Coronado Bridge.
“We’re expecting a large fault rupture, almost six feet, a lot of liquefaction impacts, which basically is softening of the soil that causes a lot of impact to underground infrastructure like water distribution pipes,” said Heidi Tremayne, executive director of the Earthquake Engineering Research Institute. “We’re worried that coastal communities could really be lacking some basic services for many months after an earthquake of this magnitude.”
The fault begins off the coast between Oceanside and Encinitas and extends south, coming ashore in La Jolla, scientists say. From there it cuts through Old Town, Little Italy and downtown San Diego before heading offshore at the Silver Strand and stretching down the coast to roughly Tijuana.
The EERI study estimates that the quake would inflict $38 billion in building and infrastructure damage — displacing 36,000 households and disrupting San Diego's $245 billion economy.
The report’s authors don't believe that a quake is imminent on the Rose Canyon Fault, which appears to produce a major temblor roughly once every 700 years. The last significant quake, measuring 6.0, occurred in 1862. Previous research has shown there’s an 18% chance of a 6.7 or greater magnitude earthquake occurring in San Diego County at some point in the next 30 years in San Diego County.
EERI is a national technological society whose scientists and engineers evaluate the risk and consequence of large quakes in places like the Bay Area and Seattle's Puget Sound. The group collaborates with the government and first-responders to mitigate potential disaster.
The institute’s researchers recommend that the county conduct its own study of its utilities and infrastructure to better understand the regional risks. The county, meanwhile, is considering both short and long-term solutions.
“In the short term, I would consider getting a group of regional experts together and take a look at these recommendations and determine maybe a way ahead and mitigate some of these things so we’re better prepared if in fact we have an earthquake along this fault,” said Gary Johnston, the chief resilience officer for the San Diego County Office of Emergency Services.
Branches of the fault exist beneath San Diego International Airport, which handles nearly 70,000 airline passengers a day, as well as the San Diego Convention Center and Tenth Avenue Marine Terminal.
