A seismic study of faults beneath West Hollywood has prompted city planners to consider new development measures in their revision of the city's general plan to guard against earthquake dangers.
In a 52-page report recently submitted to the city's General Plan Advisory Committee, seismic consultant Rachel Gulliver said more accurate locations have been determined for two underground faults that run along the northern and southern edges of the city.
According to Gulliver, a geologist and former Los Angeles building and safety commissioner, the northern fault--known as the Hollywood fault--runs beneath Sunset Boulevard at the base of the Hollywood Hills. A second one, the Santa Monica fault, clips the city's southern boundary with Los Angeles, a densely built commercial area that includes Cedars-Sinai Medical Center, the Beverly Center shopping mall and several incomplete hotel projects.
Although geologists have known the locations of the faults for several years, Gulliver said, West Hollywood government officials have been relying on outdated information provided by a 7-year-old county seismic study. That study showed one fault running through the center of West Hollywood.
"The delineation of the fault incorporated in earlier county documents was inaccurate," Gulliver said. "We have better information now, and that will help the city to improve its seismic planning."
Gulliver described the two West Hollywood faults as "potentially active," which means that they have not been known to cause any surface movement in the past 11,000 years. Known active faults, such as the San Andreas fault, are considered much more dangerous by geologists.
With potentially active faults, there is often not enough available information to determine their rate of activity, Gulliver said.
The potentially active designation has concerned city officials enough to prompt the 17-member Planning Committee--which has been working for more than 14 months on the revision of the city's general plan--to address new development issues.
Community Development Director Mark Winogrond said the city is considering requiring developers of new projects near the faults to do more intensive seismic tests, forcing some new projects to be designed to withstand earthquake pressures and keeping vital emergency services such as police and fire stations away from the fault areas.
"If these are indeed potentially active faults, any earthquake might affect land uses in the area," said Winogrond, who is working with the Planning Commission on the general plan revision. "Anything of significant size in the area could be damaged."
Elwood Tescher, a planning consultant who is heading the revision, said most existing buildings would be unaffected by whatever actions the Planning Committee takes. (At least 100 unreinforced brick buildings have been found in West Hollywood, and the city must submit plans by 1990 to the state on shoring up these structures.)
"Most buildings have either been designed to withstand quake pressures or else have updated their emergency procedures to deal with the potential of an earthquake," Tescher said.
Joe Cobarrubias, the chief geologist for the Los Angeles Department of Building and Safety, said his office has been aware of the fault locations. Cobarrubias said he expected such information to have no impact on existing major Los Angeles structures such as Cedars-Sinai and the Beverly Center.
"They obviously are already required to have detailed emergency plans for dealing with any earthquake," Cobarrubias said.
Spokesmen for both the Beverly Center and Cedars-Sinai said their structures are properly reinforced and detailed emergency plans have been drawn up. "We comply with the strictest city quake codes," said Gayle Cantro, marketing director for the Beverly Center.
"When the medical center was built 10 years ago, it was built to withstand a tremendous seismic shift," said Ron Wise, Cedars-Sinai spokesman. "We're confident in the precautions we've taken."
But the new information about the potentially active faults could play more of a role in the progress of a West Hollywood building that is still in the design stage.
The $80-million, 16-story, 500-room luxury hotel and retail store project planned by developers Arthur Lawrence and Lorraine Howell would occupy 2.5 acres on San Vicente Boulevard just north of Beverly Boulevard, across the street from Cedars-Sinai and close to the Santa Monica fault.
"Wherever you have a major fault line, you want to avoid any risks in high-occupancy structures," Tescher said.
Depending on its proximity to the fault, such a large building might require extra seismic tests and special designs to prevent major quake damage from ground shaking, fault ruptures or liquefaction, in which water mixes with sand and loose soils and becomes a volatile substance like quicksand, often tearing loose ground moorings and foundations.