CONCORD (CBS SF) — The Concord Fault is causing concern among Bay Area planners who worry that its 11-mile fracture zone is capable of producing a catastrophic earthquake that would impact regional and statewide fuel distribution.

A December study by the Association of Bay Area Governments found aside from the San Andreas and Hayward faults, all but two of the five Bay Area refineries, which are responsible for 40 percent of the state’s total barrels of crude in 2012, are within a couple miles of the Concord Fault.

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“The Concord Fault is significantly more active than the fault that caused the Napa earthquake,” Chris Wills of the California Geological Survey told the Contra Costa Times. “Nobody would be surprised if a magnitude-6 earthquake happened on the Concord Fault tomorrow.”

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A recent U.S. Geological Survey estimate indicates a 3 to 4 percent probability of a magnitude-6.7 or higher earthquake over the next 30 years on the Concord or lower Green Valley Fault. That’s compared with 6.4 percent for the San Andreas and 14.3 percent for the Hayward Fault.

Still, even if the Concord Fault only produced a 5.0 quake, it could cause significant damage to refineries.

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Without gasoline, other crucial needs including water, electricity and transportation, would be affected.