Los Angeles Mayor
Under the new rules, the city is requiring developers to study whether faults run under their projects. The regulations apply to parts of the Santa Monica, Hollywood-Raymond and Palos Verdes fault systems. Other faults are already subject to this level of scrutiny.
The announcement comes after a Times investigation in 2013 found that Los Angeles officials approved more than a dozen construction projects on or near well-known faults without requiring seismic studies to determine whether the buildings could be destroyed in a major temblor.
At the time, Los Angeles building officials said they were not required to order comprehensive seismic studies because the state had not yet officially designated the area as an official earthquake fault zone. Critics, however, argued that the city wasn't doing enough to make sure these new buildings were safe.
In general, California law bans construction on top of faults and requires extensive studies before approving projects within about 500 feet of faults zoned by the state. But decades of state budget cuts delayed the mapping of crucial fault zones in Los Angeles.
If there's no state zone, cities aren't required to enforce the law.
But scientists have identified many earthquake faults across Los Angeles that the state has not officially mapped. Cities have the power to use existing data to draw their own fault zones and require fault studies, but many don't.
On Friday, Garcetti said the new rules are part of his larger seismic safety campaign, which includes seeking mandatory retrofits of thousands of wood and concrete buildings at risk of collapse during a big quake.
"It's important that new buildings be as safe as they can be, and this new measure helps ensure our buildings are built on solid ground," Garcetti said in a statement.
California geology officials welcomed the city's new zones.
"It definitely is a good step, because we want to make sure that the public is protected," California Geological Survey engineering geologist Brian Olson said. "That's not only the job of the state, but also local government as well."
With new funding granted to state geologists in 2014, Olson and his colleagues are now working on drawing state earthquake fault zones for the Santa Monica and the Hollywood-Raymond fault systems. Drafts could be released as early as this fall.
Building on top of an active earthquake fault is dangerous, state officials said. During the 1971 Sylmar quake, one side of the San Fernando fault shifted as much as eight feet. About 80% of the buildings along the fault suffered severe to moderate damage.
"Why would one risk constructing multimillion-dollar investments on ground that is known to be of very high hazard, and place in jeopardy the lives of those who inhabit the building?" John Parrish, the state geologist, asked in 2013.
Other cities have taken the initiative to draw their own earthquake fault zones where the state has not.
After the Northridge quake hit in 1994, the city of West Hollywood, expecting a boom in development along Sunset Boulevard, created a fault precaution zone.
Since 1997, developers have conducted more than 25 detailed geology studies and redrawn some designs so that buildings would be constructed away from the fault, West Hollywood planning officials said.
California officials praised West Hollywood for ordering those studies.
"It really helped them and their community ... especially when CGS didn't have the funding," Olson said. "To just allow and wait for one agency to come up with these maps is not helpful."
The new push to map earthquake faults in Los Angeles came as officials questioned whether a fault existed beneath the Millennium Hollywood project, a proposed development of 39- and 35-story skyscrapers in the heart of Hollywood.
City officials last month agreed with the developer that a fault probably runs under the site but is too old to be active. Project opponents say that conflicts with the state geologist's conclusion last year that the fault is active.