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SCIENTISTS DEBATE MERITS OF GREEK EARTHQUAKE PREDICTION METHOD.

Byline: Felix Sanchez The Riverside Press-Enterprise

A new method of earthquake prediction promoted by Greek scientists warrants continued study to see if it is reliable, UC Riverside researchers said.

The key will be finding out whether unusual underground electric fields found where there is underground stress are actually the precursors to big quakes. The electrical activity has been observed only in Greece, which has 10 times as many earthquakes as California.

Debate over the VAN method of predicting earthquakes is the subject this week of an entire issue of the American Geophysical Union's publication, Geophysical Research Letters.

Developers of the VAN method said it is possible to predict earthquakes by measuring abnormal electrical activity in the ground.

Panayiotis Varotsos of the University of Athens said that he has correctly predicted the location, time and magnitude of a number of earthquakes using that method.

Critics said VAN's accuracy rate is not any more successful than using random chance, the ``predictions'' have been too vague, and claims of success misrepresent facts in some cases.

University of California, Riverside, researchers recently did a statistical analysis of the VAN method and found that additional study is needed to find out the source of the abnormal electrical fields and their role as possible quake predictors.

The source of the electrical signals may be fluids flowing along fault lines that are creating electrical fields, said UCR associate geophysics Professor Stephen Park.

The VAN method is worthy of a serious look, said Park, who is identified as a scientist generally favorable to VAN by the American Geophysical Union.

At the very least, UCR graduate student Richard Aceves said, ``It may eventually lead to a highly successful method.''

According to the UCR research, between 1987 and 1989, Varotsos predicted 28 earthquakes in Greece using the VAN method. During that time, there were 311 earthquakes in the country with magnitudes of 4.3 or higher.

Park, David Strauss, UCR statistics professor, and Aceves calculated that of the quakes VAN predicted, there was a 68 percent success rate.

But even with a 100 percent success rate, the predictions would have forecast only 9 percent of all moderate-to-strong earthquakes occurring during the 2-1/2-year period studied, Park said.

Most scientists are unconvinced of VAN's value, according to the American Geophysical Union.

Park emphasized that the VAN method is inexact science. A successful prediction was claimed by Varotsos if a quake occurred within a few weeks of the prediction, within about 100 kilometers of the predicted location, and if it reached a magnitude of 4.3 or higher.

Still, Park said there may be correlation between the electrical fields and earthquakes, so further study is warranted.
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Publication:Daily News (Los Angeles, CA)
Date:May 26, 1996
Words:444
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