April 15, 2006 6:00 AM PDT
Bright lights, big quake?
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Other precursors aren't panning out so well either, Beroza said. About five years ago, geologists discovered that low-level earthquakes appear to occur below part of Japan, similar to the rolling tremors that occur below volcanoes. Intuitively, these would seem to be a kind of precursor, but so far the data hasn't panned out.
In an attempt to get real-world data, QuakeFinder has created a network of 70 ultra-low and extremely low frequency magnetometers, along faults stretching from Mexico to Eureka in Northern California.
The sensor network likely can't predict a quake--scientists would need a network of 200 sensors with one placed every 20 miles to do that--but the devices can gather data that can be analyzed retroactively to see if a correlation exists between spikes in electromagnetism and quakes.
The company, along with France's Centre National D'Etudes Spatiales, also has sensors on satellites to detect ionospheric changes.
While not conclusive, the results raise eyebrows. QuakeFinder's sensor network revealed that changes in the electromagnetic field began to occur before the San Simeon quake of 2003 as well as nine hours before the Parkfield earthquake in September 2004. The network also detected magnetic field changes a few days before a quake near Anza, Calif. The data was significant, Bleier said, in that the Anza quake measured only 5.2 on the Richter scale, lower than the 6.0 threshold the company assumed would be needed to generate detectable signals.
Data from Demeter, a French satellite, show ionospheric changes occurring in conjunction with a number of earthquakes. NASA is also conducting experiments to determine whether minute surface movement detected by satellites can serve as earthquake precursors.
Doubt, though, abounds. A five-year program for studying electromagnetic precursors at Japan's RIKEN, a scientific institute, was killed off. QuakeFinder has landed grants from some agencies but not enough to conduct all of the experiments it would like. The U.S. Geological Survey has rejected grant applications from QuakeFinder a couple of times. Freund says that scientific prejudice is behind some of the doubt.
"I'm now actively targeting the people who are most opposed to these ideas, who generally are seismologists," he said. "Many of them are very limited in their scope."
Getting venture capitalists to invest in earthquake warning systems remains difficult, because the potential payout is almost nonexistent. QuakeFinder's private funding has come from satellite companies.
If anything, the parties at least agree on this: There's still a lot we don't know.
"We're learning new things about the earth all the time," Beroza said.
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