Fault Risk in Malibu Splits Apart the Experts : Seismology: Scientists warn of a magnitude 6 or 7 quake that could send landslides into houses. But a state geologist recommends that development be limited on only one-half mile of the system.

Seismic experts years ago concluded that the Malibu Coast Fault is active in the Pacific Ocean less than two miles from the Malibu Pier, but several scientists with extensive knowledge of the fault said their calls for further study have fallen on deaf ears.

The little-publicized work of two geologists from the U.S. Geological Survey who used sophisticated sound-imaging technology to map the fault between 1969 and 1973 raises new questions about a state investigation of the fault system.

The Malibu Coast Fault is a complex web of faults roughly paralleling the coast beneath much of Malibu and areas immediately offshore. Some geologists say it is capable of producing an earthquake of magnitude 6 or 7 that could bury parts of Pacific Coast Highway and send landslides crashing into houses.

The state is considering whether to designate the fault onshore as active, a decision that would limit construction in the affected area. Despite warnings from nearly a dozen experts that the fault is active, a geologist for the Division of Mines and Geology has recommended that only a half-mile section of the more than 45 miles of fault strands under Malibu be given the “special studies zone” label.

The internal recommendation, disclosed by The Times in February, prompted critics to accuse the state of being more concerned with property values than with life and safety.

Critics of the state’s handling of the matter say the work of geologists Holly C. Wagner and the late Arne Junger flies in the face of the state’s reluctance to declare the fault active.

“If you’re going to do a proper, comprehensive investigation, you cannot just restrict yourself to the onshore portion of the fault system,” USGS geologist Gary Greene said.

Greene, co-editor of the most extensive map series available of quake faults along California’s 1,100-mile coastline, said scientists have for years appealed to the Geological Survey and the state Division of Mines and Geology to follow up on the work of Wagner and Junger.

“Unfortunately, the response has been zero,” he said. “It seems there is never enough money and there are always other priorities.”

Under the Alquist-Priolo Act, passed soon after the 1971 Sylmar earthquake, construction of high-occupancy buildings such as schools, hospitals and commercial projects is prohibited within 50 feet of the site of a fault’s intersection with the Earth’s surface. The law also requires sellers to disclose to prospective buyers that their property is within such a zone.

In Malibu, which contains some of the state’s highest-priced real estate, such zoning could significantly curtail development, especially in the largely undeveloped Civic Center area where many of Malibu’s businesses are located.

James E. Slosson, a former state geologist who is on the state Seismic Safety Commission, is among several prominent geologists who say the fault system is active, and who have suggested that new legislation be enacted, if necessary, to enable the state to declare it so.

“We can argue about Alquist-Priolo all day long and miss the big picture,” he said. “And that is, that fault is active and capable of causing widespread death and destruction.”

The state began its investigation in May, 1991. State geologist James F. Davis is expected to make a final decision on the fault’s designation sometime next year.

Davis, who has faced criticism from other geologists, also has been forced to defend the state’s evaluation before Malibu officials, several of whom have expressed skepticism about it.

Some critics have accused the state of seeking to placate powerful Malibu development interests, something Davis and other officials have denied.

Sources familiar with the state’s evaluation say that although officials began gathering information about the work of Wagner and Junger last year, the Division of Mines and Geology had given it short shrift until recently, when members of the Seismic Safety Commission began inquiring about it.

Wagner, 71, is now retired and works part time for the U.S. Geological Survey in Menlo Park. Junger, who died several years ago, was a well-known marine geologist who worked for Shell Oil exploring offshore petroleum deposits in Europe and elsewhere before joining the Geological Survey.

Wagner said he had not been contacted by the state and did not know until recently that the state was investigating the Malibu Fault.

“I would think the offshore data that we gathered could only be considered compelling in whatever they do,” he said.

Wagner concluded that the evidence of Earth movement he and Junger observed on two fault branches that roughly parallel the coast from Point Dume nearly to Pacific Palisades probably occurred within the last 50 years.

The state considers movement along a fault within the last 11,000 years sufficient to designate the fault as active.

The map series edited by Greene and Michael Kennedy, a geologist with the Division of Mines and Geology, used the work of Wagner and Junger as well as other data to map the offshore fault strands.

Davis, the state geologist, declined to comment on the role the offshore information may have in the state’s evaluation.

However, another top Mines and Geology official sounded an unenthusiastic note.

“We will review it. Whether we use it or not is another matter,” said Earl Hart, senior geologist in charge of the division’s Alquist-Priolo investigations.

“It is not our custom to use geophysical methods (such as those employed by Wagner and Junger) because we have the ability to trench for faults (onshore) using direct observation,” he said.

However, state officials have acknowledged that the state neither dug trenches nor bored test holes during its fieldwork in Malibu that concluded last November, citing a lack of funds.

As with other Alquist-Priolo investigations, the one in Malibu relied instead on the accumulated observations of engineering geologists who depend to a large extent on developers for their livelihood.

Several geologists said they and colleagues had observed enough evidence of recent Earth movement along the Malibu Fault to convince them that the fault system is active. However, in nearly every case, these geologists reported being dismissed by clients before they could conduct tests to confirm what they had observed.

The Malibu Coast Fault

Broken lines show suspected splays, or branches, of the Malibu Coast Fault. It’s main trace is designated by the solid line. Recently mapped offshore branches include one less than two miles off the Malibu Pier. Geologists have established that fault activity offshore has occurred in two areas in the last 11,000 years, the state’s benchmark for determining whether a fault is considered active.