One day we may be able to use weather satellites to analyze signals from within the Earth that predict an upcoming earthquake. We may also be able to explain the strange pre-earthquake behavior of weather, radio transmissions, animals and even people. But many seismologists believe that predicting individual earthquakes early enough to permit a planned evacuation is unrealistic.
Friedemann Freund and Dmitri Ouzounov, of the NASA Ames Research Center in California, have observed that earthquakes are sometimes accompanied by disruptions in radio transmissions in the ionosphere, the region of the atmosphere that begins about 50 miles above Earth. But no one knew what caused them. ?Without proof that there is a cause and effect relationship, most geologists have dismissed the phenomenon as a coincidence,? says David Jackson of the Southern California Earthquake Center.
Freund thinks that earthquakes begin several miles below the surface of the Earth. Electromagnetic waves cannot travel far through dense rocks. But Freund has discovered that compressing rock can cause positive charges to build up inside it. This can form a charge that migrates to the surface at the rate of about 300 to 900 feet per second, where it can ionize the air. This ionization could explain the strange pre-quake phenomena that is sometimes reported.
A positive charge near the surface would draw negatively charged atmospheric particles closer to the Earth. Freund and Ouzounov think that when the charged particles combine, infrared radiation is released, producing heat. They believe they can detect this signal with weather satellites about two to five days before a quake happens.
They examined data from a NASA satellite called MODIS for the days preceding the January 26, 2001 earthquake in Gujarat, India, and found that the temperature rose 35 to 41 degrees Fahrenheit in the days preceding the quake. However, Freund and Ouzounov have not yet proven that these temperature increases are due to an increased infrared signal. They are now searching through the data from the 36 different wavelength bands that the MODIS satellite monitors. They also plan to study the temperature variability in Gujarat.
Thomas Jordan, of the Southern California Earthquake Center, says if there was such a thing as a pre-earthquake heat spike, people would have noticed it years ago, and says previous satellite studies have been inconsistent.
David Jackson says, ?In order to make this idea useful, one would need to observe it at several earthquakes.?
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