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Quakes? Town points finger at a nearby steam project
Nature has been eclipsed by human factors, say rural residents
Carl T. Hall, Chronicle Science Writer
Sunday, June 8, 2003
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Anderson Springs -- A surge in the number and severity of earthquakes near the Geysers, the world's largest geothermal development, has alarmed rural neighbors and they're not blaming Mother Nature.

"These aren't natural earthquakes," said resident Connie Dethlefson, one of many citizens in this tiny community who insist that the temblor problem is a man-made byproduct of nearby steam-power production facilities.

Since 1960, "induced seismicity" has been a chronic occurrence in the area, even according to geologists at Calpine Corp., the San Jose power company that now owns most of the two dozen power plants in a 30-square mile area along the Sonoma and Lake county line. The facilities, built on ridgetops to stay clear of landslides, draw steam from underground reservoirs.

But the controversy here turns on an apparent recent increase in shakers. In May alone, three quakes were recorded in the Geysers area: a 3.7 magnitude on May 3, a 4.0 on May 20 and a 3.4 on May 21.

Some people in Anderson Springs seem convinced that earthquakes now threaten to wreck their community's very foundations. And they believe huge injections of water, pumped deep underground at the Geysers in order to replenish the steamfields that drive the turbines, are causing the temblors.

In 1997, communities around Clear Lake began diverting millions of gallons of treated wastewater daily to the Geysers through a 29-mile pipeline project.

The pipeline is currently delivering 7.5 million gallons a day. Another 11 million gallons are due to start arriving daily from Santa Rosa later this year, although that will be delivered to a different part of the steamfields farther from Anderson Springs. Final testing of the Santa Rosa pipeline project is under way.

The idea was to provide clean energy and give the communities a handy outlet for wastewater that otherwise could add to pollution problems of sensitive watersheds.

But while environmentalists have applauded the projects, the talk in Anderson Springs lately has focused on widening cracks in old stone foundations, falling knickknacks and frazzled nerves.

"We're rockin' and rollin' all the time," said Meriel Medrano, the local water-district manager, who has had a house in Anderson Springs since 1969.

Stones keep popping out of her chimney, she said, and a vase toppled in the May 3 temblor -- one of the latest and largest quakes among hundreds that have been recorded in or near the Geysers in recent years.

"The earthquakes have been increasing astronomically," she said.

Seismic monitoring sponsored by the power companies began in the late 1960s,

bolstered in 1979 by an array of monitors installed by the U.S. Geological Survey. The data show a clear increase in the frequency of small earthquakes, and there's not much debate about the link to steam-driven energy production.

"There's no question, absolutely no question, that almost all the earthquakes are related to activities related to power production," said David Oppenheimer, a geophysicist at the USGS.

The question is whether the induced quakes are mere annoyances. Industry experts claim the quakes are almost all too small even to be felt, let alone cause any significant damage.

"An increase was anticipated in terms of these micro-earthquakes," said Dennis Gilles, a Calpine vice president for the Geysers operations. "But you get a magnitude 2 earthquake, and it's not even like a truck driving by."

But the picture starts getting a little murky when it comes to bigger quakes, those above magnitude 2.5 or so, according to Bill Smith, a senior geologist at the Northern California Power Agency, a collection of public power authorities that also operates at the Geysers.

Smith said there is no clear evidence that the Geysers are causing anyone harm, despite some increase in low-level shakings.

"We don't experience any damage here," Smith said, "not even within our own offices, and we're sitting right on top of the Geysers."

Anderson Springs residents want special monitoring. But Mark Dellinger, special districts manager for Lake County and chairman of a seismic-monitoring committee set up as part of the county's pipeline project, said a "huge investment" has already been made to keep tabs on every move the ground might make in the Geysers area.

It's been enough, he said, to make tiny Anderson Springs, which lacks even a post office or a single commercial establishment, a unique laboratory for seismic research in a geothermal area.

"I doubt there is a community anywhere in the world this small with this kind of sophisticated seismic array," Dellinger said. "I don't think there's any conclusive evidence to support any of the claims being made."

By all accounts, it will take more monitoring to determine just how serious the problem is and what might be making it worse.

The issue is complicated by such factors as local geology and faulting, frequent changes in levels of power production, and even by local construction styles in a hilly, landslide-prone area full of old homes that started as summer cottages.

The recent increase is mostly in small, shallow quakes. This could prove to be just some natural variability, an anomaly perhaps due to subside on its own.

If the root cause of the shaking turns out to be depletion of the steam reservoirs, then the additional water being injected might eventually help to reduce disturbances.

Another leading theory is that the increased seismic activity results from rapid cooling and fracturing of rocks deep underground where temperatures are normally about 450 degrees Fahrenheit. If so, problems could be worsened by the injection of millions of gallons of 50 or 60 degree wastewater from the surface.

All this does little to reassure folks in Anderson Springs.

Residents described being jolted out of bed at night by brief but sharp explosions underground, seemingly more violent all the time, sometimes hitting a house as if by a truck ramming into the front porch.

Jacqueline Felber said she and her husband had to replace 60 cracked ceramic tiles in their kitchen, where the floor lately has become noticeably bowed. Walking around outside, she pointed out some gaps in the siding, which she said have been spreading ominously of late.

After 17 years in Anderson Springs, Felber insisted that she and her artist- blacksmith husband still love their place. Still, she said, "You can see where it's starting to come apart at the seams."

No injuries have been reported. The biggest alleged casualty, however, may have been an old black oak tree that toppled across one of the creeks trickling through the unincorporated town, where bone-weary celebrities once visited to take the local waters. But no one can prove whether it was an earthquake, or perhaps a strong gust of wind, that brought it down.

Jeff Gospe, a Santa Rosa business consultant whose in-laws own a home in Anderson Springs, was adamant that local quake damage is real and getting worse, exacerbated by the wastewater projects and increased steam-power production.

"It's only a matter of time before someone gets hurt," he said.

Gospe, 35, serves as president of the recently formed Anderson Springs Community Alliance. The organization demands that the power plant companies and public agencies behind the pipeline projects create regulatory and insurance mechanisms to protect landowners and local taxpayers.

Gospe produced an armful of gigantic geology maps and a 4-inch-thick binder full of survey results, photographs and color charts showing earthquake trends.

His central conclusion, based on public data and later confirmed by Oppenheimer as essentially valid, is that something on the order of 1,900 earthquakes of magnitude 2.0 or larger have occurred within a 5-mile radius of Anderson Springs since 1970.

"They used to be just little shakers," said Alan Kuykendall, a condominium manager in Napa who spends about half his time at a home he bought in Anderson Springs in 1980. "The earthquakes are much worse now than they ever were."

E-mail Carl T. Hall at chall@sfchronicle.com.

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