California's state geologist has declared that the Hollywood earthquake fault is active and may run directly underneath a skyscraper project approved by the Los Angeles City Council last week.
The assertion raises new doubts about whether the 1-million-square foot Millennium Hollywood project — which would create two of Hollywood's tallest towers — should go forward without significantly more seismic safety testing than the city has so far required.
While the Hollywood fault has been known for several decades, geologists have never mapped its precise route on a block-by-block level. Steep slopes formed by old fault ruptures are visible from the street on both sides of the project location, where developers want to erect 39-story and 35-story towers.
Several geologists interviewed by The Times have urged more extensive testing, such as digging dozens of bore holes or a trench, to determine exactly where the fault lies. If an earthquake fault is found underneath the Millennium towers, it could force a revision of architectural plans or scuttle the project.
California law bars construction of new buildings within 50 feet of an earthquake fault declared active and mapped by state officials. A building over a fault can be ripped in half during an earthquake.
There have been questions about how active the Hollywood fault is. But the head of the California Geological Survey, John Parrish, said in an interview there is now ample evidence that the fault is active and capable of producing a devastating earthquake.
Parrish said strands of the Hollywood fault appear to run underneath the Millennium towers site near Hollywood Boulevard and Vine Street but that further tests are needed for final confirmation.
"This is a very big project that they're working on, and they should have the latest information that's available," he said.
A spokesman for the New York-based developer, Brian Lewis, said geologists did testing at the city's direction and found no evidence of a fault at the site. But he added: "We're happy to do more testing, and we fully intend to do more testing. We have no interest in building anything that would be unsafe."
The state is reviewing all known data about the Hollywood fault. In the next few months, state geologists will also perform a visual examination of the fault.
The research will culminate with the state creating a zone around the fault. The fault is not a straight line, but more like a fracture zone — like cracks in a broken piece of peanut brittle.
The Millennium project has prompted the state to accelerate its study, and it hopes to have results by early 2014.
Mapping the fault would have major implications for new development in Hollywood, which is undergoing a building boom.
Property owners along the officially drawn Hollywood fault would also be prohibited from new construction or significant renovation under the Alquist-Priolo Earthquake Fault Zoning Act, passed after the 1971 Sylmar earthquake.
The law does not affect existing buildings. But in the past, the discovery of faults has led some to take action. Los Angeles Southwest College demolished two buildings in 1991 that straddled the Newport-Inglewood fault. The Los Angeles Unified School District tore down a portion of the new Belmont Learning Center after finding that a fault ran underneath it.
USC earth sciences professor James Dolan — whose maps and studies in the 1990s are the leading source for state officials on the location of the Hollywood fault — said lawmakers had good reason for banning construction on faults.
The Hollywood fault could rupture into a magnitude 7 earthquake and could sever a building. Half of the building straddling the fault could be shoved 10 feet away from the other side, Dolan said.
"If you know where an active fault is, you just can't build on it," Dolan said. "You just don't do this when you're building structures for human occupancy."
The Hollywood fault, he added, is part of a series of faults that run east from the Malibu coast, along Santa Monica Boulevard, through Hollywood and eventually to the Raymond fault, which reaches Arcadia.
Parrish said the last time the Hollywood fault was known to have ruptured was 7,000 to 8,000 years ago. Any fault that has shown shaking in the last 11,000 years is defined by California as active.
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