for National Geographic News
In dusty California hills geologists have drilled miles into the Earth to monitor earthquakes where they begin. It's all part of an effort to better prepare the state for the type of megaquake that struck San Francisco a hundred years ago tomorrow.
The scientists are using techniques borrowed from the petroleum industry, but they're not searching for oil. Rather, they're hoping to learn the secrets of the San Andreas Fault's "earthquake machine."
The project is called SAFODshort for the San Andreas Fault Observatory at Depth. Funded by the National Science Foundation, SAFOD reached a major milestone last year when a 7-inch-wide (18-centimeter-wide) borehole was drilled sideways through the fault zone at a depth of about 2 miles (3.2 kilometers).
Most people have never heard of Parkfield (map), the central California village that is SAFOD's epicenter. But it's famous among seismologists.
The tiny town lies along a segment of the San Andreas Fault notorious for producing frequent earthquakes, ranging in size from magnitude 6 to tremors noticeable only on the most delicate instruments.
That makes Parkfield the best place along the fault to "capture" an earthquake in action, say scientists who have been studying the region since the 1980s.
And while the tremors observed here are much milder than the one that may someday do Katrina-like damage to San Francisco, seismologists hope their studies will teach them how to spot the warning signs of potential monster quakes.
Nobody knows what the project will find, because nobody has ever studied earthquakes in this way.
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