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State Releases Quake Hazard Maps Lacking Details on Faults

Officials say even limited data on areas requiring seismic studies should help plan for risks.

September 25, 2003|Kenneth Reich | Times Staff Writer

The California Geological Survey on Wednesday released the latest in a series of seismic hazard maps under a program that has come under fire for showing some earthquake hazards but not others.

The latest of the 60-square-mile maps show areas near Acton and Pacifico Mountain, in the San Gabriel range, where an earthquake stronger than magnitude 5.5 could be expected to generate landslides or soil liquefaction.

All of Orange County and most of Los Angeles County have been covered in the maps, which designate "zones of required investigation" where geological studies must be mandated by local agencies before building permits are issued. Property owners and real estate agents must tell prospective buyers that those areas have been designated seismic hazard zones.

In a significant omission, however, earthquake faults are not shown on the maps, and neither are areas where the so-called near-source effects of large quakes could be extremely damaging.

The maps released Wednesday do not include liquefaction and landslide zones in areas of the Angeles National Forest and are limited to ranching and rural residential areas outside the forest.

The California Geological Survey is part of the state Department of Conservation, whose director, Darryl Young, said Wednesday that the program, even in its limited form, defines certain problem areas.

"Once you define the problem, you can take steps to minimize the danger," he said.

The state has issued 75 maps in Southern California and 18 in the Bay Area.

An additional 13 maps, including several in Los Angeles and Ventura counties, are under review.

The present state budget calls for $3.5 million to be spent this fiscal year on the mapping program, with the money coming from building permit fees and not the general fund.

Initial funds for the maps came largely from the Federal Emergency Management Agency after the 1994 Northridge earthquake, but those grants have been exhausted.

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