Prediction Claims Stir Greek Controversy

Bucking any scientific consensus can be rough, but insisting that you can predict earthquakes in a quake-prone country like Greecewhen practically no one thinks it can be done anywhereis sure to create a fuss. For almost 2 decades, a group of Greek scientists has claimed they could predict damaging earthquakes by monitoring electrical currents in the ground. Although many Greek colleagues have questioned the scientific rigor of the method (called VAN, after the initials of its inventors), a run of seeming successes in 1995 caught the attention of researchers outside of Greece ( Science , 10 November 1995, p. [911][1]). Now, after a lull, the VAN scientists are making new claims. They say the ground gave clear warning signs of the 7 September earthquake that struck near Athens, killing 67, and they think they may have picked up signs of another, perhaps larger, temblor in the offing. These claims are meeting with scorn, especially in the Greek scientific community. This has nothing to do with seismology or science, says Leonidas Resvanis, director of the Physics Laboratory of the University of Athens. Adds Gerry Chouliaras, a seismologist at the National Observatory of Athens: There's no scientific reason to make this alarm. I don't believe their signals. I'm not going to believe anything. This rancor has emerged over years of frustration with VAN, explains seismologist Robert Geller of Tokyo University. Outsiders must compare vague predictions made on the basis of ill-defined criteria against the earthquake record, he says, while being denied access to the full VAN observations. The controversy began in the early 1980s with laboratory experiments conducted by solid state physicist Panayiotis Varotsos of the University of Athens and his colleagues. They found that rock squeezed in the lab produced a transient electrical current just before fracturing. Might it also give off electrical signals before fracturing under stress in Earth's crust, they wonderedthat is, during an earthquake? To find out, they set up what amount to giant voltmeters around Greece: up to several kilometers of wire connected to two electrodes stuck in the ground. Their equipment turned up signals aplenty, including extraneous currents such as radio broadcasts and industrial noise. But once Varotsos and his colleagues thought they could recognize and weed out noise, they identified seismic electric signals, or SESs, that seemed to precede quakes of all sizes in Greece. Some seismologists were intrigued, but many objected that any apparent VAN successes were just dumb luck; by making enough predictions, the VAN group was sure to catch a few of the many quakes that strike Greece each year. Unfazed by such objections, Varotsos and his colleagues expanded their monitoring. On 1 and 2 September, a station near Lamia, about 150 kilometers northwest of Athens, recorded the first powerful signal in its 4 years of running, says Varotsos. He and his University of Athens colleagues, physicists Vassilios and Claire Hadjicontis, say they immediately recognized the signal as the SES of a significant forthcoming earthquake. They concluded that the SES signaled a magnitude 5.5 quake that would strike something like 70 kilometers away sometime in the coming few weeks. The Athens quake came 5 days later, 140 kilometers away, with a magnitude of 5.9. It is very impressive to see the signals and expect an event, says Claire Hadjicontis. I think it's very promising. The VAN group never made this prediction public, according to Varotsos, because of an understanding with the Greek government that they would only announce predictions of imminent quakes of magnitude 6.0 or larger. But Varotsos soon thought he had another prediction, which did fit the bill. The signal of 1 to 2 September, he had noticed, changed polarity before disappearing, something that had happened before when a single station had picked up merged SESs from two impending quakes. Then, on the 13th, the Lamia station picked up another SES of the same polarity as the end of the earlier signalseemingly a continuation of the first. This strengthened our interpretation that the last part of the signal should correspond to future activity, Varotsos told Science on the 14th. On the 16th, VAN group member Kostas Eftaxias went public on national TV with both their postdiction of the 7 September quake and suggestions of another impending temblor somewhere around Lamia, this time with a magnitude of about 6.0. Chouliaras is not impressed. It is ridiculous to continue this debate, he says. In recent published papers, he says, he and colleagues have shown that the SES-like signals they recorded independently at the VAN station in western Greece are radio and phone transmissions, not crustal signals. Resvanis also remains to be convinced. If they did predict [the 7 September quake], it would be random coincidence, he says. Adds Geller: His predictions are on the same level as those of the oracle at Delphi. To be taken seriously, he says, the group needs to change its ways. Varotsos is simply not carrying out scientific research as it is understood by scientists. None of the necessary conditionsfree availability of continuous raw data, publication of the prediction algorithmare satisfied. Even those who have offered some support in the past are being cautious. Stephen Park of the University of California, Riverside, says he would back off and take a little more conservative view than in '95, when his analysis suggested VAN was doing better than chance at predicting quakes. With a longer VAN record to work from, Park now finds that any claims of real success could be questioned by statisticians. Varotsos has answers to all these criticisms. For example, he acknowledges that he and his colleagues record a lot of noise, but we apply certain criteria and immediately classify noises versus signal, and he can point to a published algorithm. But he gets the feeling that his critics are actually sending a broader message: The problem [of earthquake prediction] is very difficult, and therefore no one should try. Varotsos insists he must, although he now faces both the mysteries of earthquakes and the deep skepticism of his colleagues. [1]: /lookup/volpage/270/911