A-Bomb’s Birthplace Ponders New Risk--a Volcanic Explosion : Geology: Federal cutbacks aren’t the only worry facing Los Alamos, N.M. Scientists think a neighboring caldera may pose an eruption threat.

Central New Mexico’s Valles caldera was known as a placid expanse of dormant volcanoes, meadows and meandering trout streams just up the road from the super-secret laboratory that gave birth to the atom bomb.

That was before geologists John Wolff and Jamie Gardner concluded that the volcanic field within spewing distance of the Los Alamos National Laboratory may be gearing up for a new cycle of eruptions.

On Tuesday, they called on the federal government to install a monitoring system in the caldera that could detect seismic warnings of an impending blast that could shower the laboratory and surrounding communities with ash, acrid smoke and hot rocks. They also said residents should consider storing protective face masks and hard hats.

But even permanent monitoring may not provide ample warning for the 18,000 people who reside on the flanks of the caldera that towers over this high desert landscape of canyons and plateaus. Geological features in the caldera’s plumbing system, they said, might conceal signs that magma is gushing toward the surface.

“We are raising a warning flag here; prior to our study, this was thought to be a dying volcanic system,” Gardner said, standing on the rim of the caldera that was draped in pumice chips ejected during the last eruption. “I feel a personal and professional obligation to tell people about this so they can acknowledge the hazard, monitor it and prepare for it.”

There is never a good time to be told there is a restless volcano in the neighborhood. But for officials in this clean and nearly crime-free unincorporated community northwest of Santa Fe, the warning now holds special perils.

It comes at a time when deficit hawks in Congress want to downsize the Department of Energy’s $5-billion nuclear weapons research laboratory, which remains the major employer in what amounts to a remote and isolated “federal company town.”

Fearing that cutbacks are imminent, Los Alamos County officials are trying hard to attract new industry that could offset their economic dependence on the laboratory, which sustains a work force of 14,000 scientists, engineers, technicians and contract employees.

They have already been told that special “federal assistance payments,” which help the county maintain basic services, will end in 1996. Those payments have provided the county with 15% of its annual general operating budget since 1967.

But efforts to lure new businesses here have been hampered by some harsh realities about the town perched on Pajarito Plateau and surrounded by federal land, private holdings and Native American reservations.

The federal government controls 90% of the county’s 110 square miles, leaving precious little land on which to develop sorely needed private industry and affordable housing. The cost of living here is 25% above the national average, housing costs are 60% higher. There are two roads leading into the community, and one of them winds over the caldera.

“This is just another bump in the road toward diversification,” sighed Fred Bruggeman, who heads up the county’s development department.

“Just as some places do earthquake and forest fire planning,” he said, “I guess we’ll have to do something about where the likely lava flows will be.”

Other residents, however, were quick to poke fun at the geologists’ findings.

“Not to worry, surely some federal bureaucracy will outlaw lava flows,” quipped local realtor Jim Gautier.

“On the other hand, we don’t have tornadoes, floods, crime problems or traffic snarls,” he said. “So, maybe the threat of a volcanic eruption will liven things up around here.”

It’s no joke for Wolff, associate professor of geology at the University of Texas at Arlington, and Gardner, a geologist at Los Alamos National Laboratory.

Although the chance of the caldera exploding right now is slim, the fact that it could led them to ask for equipment to monitor changes in temperature, earth movements and other activity that could presage an eruption.

“The chance of a $100,000 home burning down is a million to one--but you still spend $10 on a smoke detector,” Wolff said. “When you think about the billions of dollars spent at Los Alamos National Laboratory, that metaphor becomes more exact.”

Wolff and Gardner base their calculations, in part, on a study of the crystalline structure of rock ejected from the caldera during its last eruption 60,000 years ago--relatively recently by geological standards.

Observed under a microscope, details in the texture of those rocks indicate that they were melting back into the magma before it surfaced, rather than precipitating out of it, they said.

“That suggests that the whole system was heating up at the time of the eruption,” Wolff said. “The longevity of this new cycle is dependent upon how much magma is being shot into the crust.”

Earlier studies detected a hot molten area about six to 10 miles beneath the surface, Wolff said, and another much larger one about 18 miles down. But scientists have yet to conduct studies that could tell whether the caldera’s surface is being raised by heaving magma below.

“That magma could sit there for a million years and do nothing, or it could begin moving toward the surface tomorrow--and once on the move it could take a matter of days to reach the surface,” Wolff said.

A volcanic blast, Gardner added, would probably be confined within the walls of the caldera, which is 15 miles across and 1,000 feet deep. The main hazard would come from ash fallout, which would be costly in terms of cleanup, but not necessarily life-threatening.

In any case, laboratory officials said the 43-square-mile facility’s nuclear storage bunkers would not be jeopardized because they were designed to withstand a massive earthquake.

Not all volcanologists agree with the scenarios laid out by Wolff and Gardner. Dan Miller, a research geologist at the Cascade Volcanic Observatory in Vancouver, Wash., said: “While it is certainly possible that there could be another eruption, it is less likely that the Valles caldera would produce an eruption in our lifetimes than a volcano in the far Western United States.

“What would get my attention in the Valles caldera,” Miller added, “would be swarms of earthquakes that might suggest the magma was moving.”

The caldera has been seismically quiet for decades.

Nonetheless, laboratory spokeswoman Kathy De Lucas said the facility would initiate a contingency plan in coordination with the U.S. Geological Service.

As its stands, she said, “we do conduct annual hazard assessments and the volcanic hazard is low on our list.”