Evidence Mounts for Electromagnetic Earthquake Precursors
By Keay Davidson
SAN FRANCISCO –- Scientists revealed data Thursday that an electromagnetic alarm might have preceded a 2007 earthquake in Northern California. The evidence could offer support to a controversial theory that mysterious and little-understood signals might offer fair warning for imminent catastrophic earthquakes.
A long-time proponent of the earthquake-alarm theory, Friedemann T. Freund, a scientist at NASA Ames Research Center in Mountain View, California, also presented data on the possible mechanism underlying the electromagnetic signals.
He reported the result of a lab experiment in which he subjected rock to high pressures, modeling pre-earthquake conditions. It caused the rocks to develop electrical currents, he said. After relieving pressure on the rock, the electrical current slowly faded out — just like the electromagnetic measurements after quakes.
“Either there is a big devil down there moving magnets back and forth, or there is some kind of physical effect causing (these signals),” Freund said.
Johnston, however, said Freund’s electrical currents would be “short-circuited” by the abundant groundwater in underground rock.
Still, with evidence mounting that the signals might be real, some scientists are calling on the federal government to develop a network of electromagnetic sensors to detect such signals before quakes. Even skeptics agree more detection is necessary.
“We need a much more comprehensive (electromagnetism-monitoring) network,” Johnston said.
But Bill Ellsworth, a prominent Geological Survey geophysicist, said that in the absence of an infinite amount of federal funding, first priority should go to the development of more seismic-detection networks that — unlike earthquake alarms — are based on well-understood physical principles.