State Urges Controls in Mapped Quake Zones

California took a step Tuesday toward more extensive land use controls in urban areas designated as seismically hazardous, and officials said that in extreme cases, building permits could be withheld from developers who fail to sufficiently protect against quakes.

Another new requirement is that owners of all properties in the zones deemed hazardous, including single-family homes, disclose the hazards to buyers when the properties are sold.

The issuance of the first five of 38 official maps is supposed to trigger requirements by building departments that developers conduct geotechnical studies in hazardous areas and submit plans for reducing the hazards when they build.

The new building permit guidelines, however, exempt most single-family homes built individually, and enforcement is left up to local and county building departments. The state has been given no authority to coerce local officials into implementing uniform standards, although it is publishing guidelines.

The individual 60-square-mile maps released Tuesday by the State Division of Mines and Geology showed areas of possible quake-induced liquefaction and landslides in the Simi Valley, a swath of Orange County from Anaheim to Newport Beach, and a large part of San Francisco.

Most other urban areas of Los Angeles and Orange counties, and part of Ventura County, will be covered by maps to be released by mid-1998. The new requirements are supposed to be implemented beginning 10 days after the maps are available.

All the maps released Tuesday were issued in preliminary form several months ago. After a public comment period, they were issued officially Tuesday with only a few revisions.

Liquefaction occurs when water-saturated soils turn to jelly under heavy shaking. In earthquakes, landslides are also common in hilly areas.

But the maps do not show fault lines. They also do not incorporate recent scientific findings about the extremely heavy shaking that occurs very close to major quake epicenters, regardless of soil conditions.

State Geologist James F. Davis told a Los Angeles news conference that detailed shaking maps may also become available and be applied later. The present hazard maps “don’t do it all,” he said.

At present, there are no funds available to prepare maps throughout the state, so the program will be confined to some, but not all, urban areas.

Davis cautioned that some of the hazardous areas may be more dangerous than others, and he said that local and county authorities may call for more stringent studies and mitigation plans in some areas.

Karl Deppe, assistant chief of the engineering bureau of the Los Angeles Department of Building and Safety, who also took part in the news conference, warned that some of the measures approved by local authorities to reduce hazards could be quite costly. Despite that, the initiative for doing geotechnical studies and preparing quake mitigation steps will remain with private developers, he said.

His department will not give instructions to the developers, Deppe said, but it will reserve the right to reject their studies and mitigation plans if it is not satisfied with them.

On the other hand, Deppe added, “there may be areas where it would not be economically feasible to mitigate the hazards.” In those situations, projects may be allowed to go ahead, he said.

Individuals who want to view the state maps will be able to obtain them through the Internet at https://www.consrv.ca.gov/ dmg/shezp. Maps will also be available at county building department offices.