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
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 to 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.
For many people, earthquakes are synonymous with unpredictability. They strike suddenly on otherwise normal days, and despite all the achievements of
seismology, scientists still can't provide warning of an impending quake in the way that weathermen warn of approaching storms.
Although earthquakes seem to strike out of the blue, the furious energy that a quake releases builds up for months and years beforehand in the form of
stresses within Earth's crust. At the moment, forecasters have no direct way of seeing these stresses or detecting when they reach critically high
Electrical currents in rock
might explain another curious observation:
Scientists doing research with magnetometers just before major earthquakes have serendipitously recorded tiny, slow fluctuations in Earth's magnetic
field. One example happened during the Loma-
[edit on 7/6/2006 by Fringefellow]