SAN JOSE, Calif. — Earthquake scientists are striving to save a pioneering project buried 2 miles under a pasture in California’s Central Valley that could one day reveal the hidden mechanics of quakes such as the one that recently jolted
SAN JOSE, Calif. — Earthquake scientists are striving to save a pioneering project buried 2 miles under a pasture in California’s Central Valley that could one day reveal the hidden mechanics of quakes such as the one that recently jolted Napa — and the inevitable “Big One” to come.
Despite renewed urgency, the once-heralded San Andreas Fault laboratory is out of money. And now, it is uncertain whether scientists ever will achieve their quest — witnessing the birth of a small earthquake on the fault that threatens millions of Northern Californians.
“Important things are often not easy,” said Steve Hickman, a geophysicist with Menlo Park’s U.S. Geologic Survey, who, with project co-leaders Mark Zoback of Stanford University and Bill Ellsworth of USGS, devoted the past decade to the project in rural Parkfield and is recruiting support for its completion.
Their goal is ambitious, both in terms of money and technology. They seek to put seismic sensors at the bottom of a hole 2 miles deep to discover: How does an earthquake start and stop? Does it send signals before it ruptures? What controls its timing and severity?
But the San Andreas Fault Observatory at Depth project has lacked the engineering expertise and the $3 million to $10 million needed to answer these questions.
The $25 million drilling of the borehole in the mid-2000s was applauded as a great success. It yielded 1 ton of 4-inch-diameter rock cores that were distributed to labs around the world, and identified a water-saturated clay as key to understanding how the San Andreas sometimes just creeps, rather than ruptures.
But the second half of the project — installing a permanent observatory inside the borehole, then drilling a second hole — failed because of a shortage of money and time. They encountered a tough engineering problem: how to keep sensitive equipment intact deep inside the Earth.
Initial instrumentation failed, then money ran out.
Now the National Science Foundation, which paid for most of the initial experiment, says it is no longer soliciting proposals for new experiments there. This winter, it will review the decision and any new proposals, said James Whitcomb, who leads the NSF’s deep-earth processes section in Arlington, Va.
“It is a difficult environment in which to work, putting dependable instruments in place down there,” Whitcomb said.
Funding is highly competitive and, he noted, several smaller, worthy projects could be supported for the cost of the single observatory experiment.
Meanwhile, only temporary instrumentation is in place. Additional tools are used at the surface. A University of California, Berkeley, team just received money to study changes in seismic vibrations in the borehole, a short-term project.
But top scientists are bidding to win back NSF’s support. University and U.S. Geologic Survey investigators say they are working with engineers who could oversee the project, even expand it, and they plan to submit an unsolicited bid for funding.
The setting for the fault observatory seems serene. Cows outnumber residents in the rural Monterey County community of Parkfield, a former mining town.
But beneath it runs the San Andreas Fault, the infamous, 800-mile-long rupture stretching nearly the entire length of California. Two restless tectonic plates that shape our continent collide along it — triggering some of the world’s most damaging earthquakes.
The fault has ruptured near Parkfield seven times since 1857, most recently setting off a magnitude-6 earthquake in 2004. (The town’s motto: “Be Here When It Happens.”)
The observatory site is unique: While one section of the San Andreas Fault creeps smoothly, not causing earthquakes — another, only 100 yards away, is locked up, with repeated fits of small ruptures. Why are they so different?
Now, scientists must infer such seismic processes in lab experiments with simulated fault rocks.
Although drilled samples reveal how the creeping fault works, what is missing are samples and measurements within the active patch. If deployment of a full observatory in the existing hole succeeds, scientists hope to drill a hole off the existing one, directly into the rupture patch.
“Laboratories don’t represent a real fault,” said University of Wisconsin seismologist Cliff Thurber, who organized support for the project in a letter 36 scientists signed.
“There is nowhere else in the world where you can have borehole instruments right next to an earthquake,” he said. But other nations have drilled down to set up their own research.
The project has been challenging from its start, Thurber and Hickman said.
Time and money were lacking to develop, test and troubleshoot all the observatory components.
The first instruments were destroyed within three weeks, victims of a leak in the housing meant to protect them from high-pressure water in the hole.
Better engineering, more funding and a carefully phased-in approach could address the risks, Thurber and Hickman said.
“There are challenges, but we need to finish the job,” said Hickman. “What we learn will help us understand the physical processes controlling earthquake generation around the world.”
