Technology: Waiting for the big one - There is growing scepticism about Japan's earthquake prediction programme
Some 160km west of Tokyo in Japan's coastal Tokai region is what may be the world's most dense array of geophysical instruments. More than 150 meters and gauges track seismic activity, rock strain, crustal tilt, tidal movements and ground water levels. The data are telemetered to Tokyo where they are monitored around the clock in the hope that six experts, to be summoned at a moment's notice, will recognise unusual phenomena that may indicate an imminent earthquake. If the committee so advises, Japan's prime minister will issue an earthquake warning for the Tokai area. Trains will be stopped, traffic routed out of the area, stores closed and pupils let out of schools. Areas prone to landslides and tidal waves will be evacuated. Hospitals, firefighters and rescue crews will go on alert. And then everyone will wait for an earthquake measuring eight on the Richter scale. Long after the rest of the world has abandoned hope of predicting earthquakes, Japan continues to spend Dollars 2.5m (Pounds 1.6m) a year monitoring the Tokai region and close to Dollars 100m more on general earthquake prediction research. For prediction believers, it is a small price to pay, as Japan is one of the world's most earthquake-prone countries. But for increasingly vocal sceptics in Japan, it is at best a misguided effort that wastes money and is dangerously misleading the public. Despite the protests, however, Japan's earthquake prediction programme rolls along on inertia, insularity and unrealistic public expectations. Japan made earthquake prediction a national project in 1965 when scientists throughout the world were optimistic about prediction. Research was also being taken seriously in the US, Russia and China. In Japan, prediction took on urgency when seismologists concluded that the Tokai area was overdue for a significant quake. The Suruga Trough, a deep submarine trench running just offshore, forms the boundary between two of the earth's tectonic plates. The Philippine Sea Plate is diving beneath the Eurasian Plate. Friction between these plates causes the area's earthquakes. The Tokai section last ruptured in 1854. If the entire section ruptures again, the resulting quake could reach eight on the Richter scale, endangering the lives of 10m residents in the area. That prospect led to the 1978 Large-Scale Earthquake Countermeasures Act, which established the warning procedure and launched hazard mitigation and emergency response programmes. Since then, optimism about prediction has faded. Even prediction supporters admit there is no scientific theory on which to base a forecast. Prediction hinges on spotting anomalous phenomena, or precursors. Unfortunately, it has proved impossible to conclude consistently and definitively whether the signspredictors look for - swarms of small earthquakes, unusual bulges and creeps in the earth's crust, sudden changes in geomagnetism or electrical resistivity - are precursors or simply background geologic noise. Precursors are often only recognised as such after a large earthquake. And many earthquakes occur without any identifiable precursor, even in retrospect. There are also questions as to whether Japan's monitoring efforts are focused in the right place. Recent studies by seismologists at the Ministry of Construction have indicated the possibility of a significant quake occurring in the Izu area between Tokai and Tokyo. The city is overdue for a big quake, according to several theories. Japan has had numerous killer quakes outside the Tokai monitoring network, including a 7.8 earthquake off the coast of Hokkaido last year that claimed more than 200 lives. Kiyoo Mogi, chairman of the six-member panel that will make the call on the Tokai earthquake and former head of the University of Tokyo's Earthquake Research Institute, says several factors make the Tokai region more suited than others for what he calls 'a national experiment'. The region's geology is straightforward, so they can narrow down the likely location of the anticipated earthquake. Historically, strain along the Suruga Trough has been released in infrequent large earthquakes, rather than numerous small ones. The evidence is that significant strain has accumulated along the fault since the region's last big earthquake. Recognising precursors will still be difficult. Mogi says they now believe that precursor patterns may be particular to each section of a fault. He says if they knew what precursory phenomena occurred the last time that section of the fault slipped, in 1854, they would be able to predict the next earthquake. Instead, the six experts are watching for the rapid uplift of the crust on the westward side of the trough that preceded quakes along adjacent sections of the fault in 1944 and 1946. This all makes a successful prediction a long shot. Aside from the Tokai effort, scientists outside the programme are disturbed that it is so generously funded and has so little to show. Prediction research elsewhere withered as scientists who could not convince review committees of the scientific merit of their research lost their funding. Japan's prediction research activities, primarily overseen by the Ministry of Education, Science and Culture, are subject to no such review. A sub-committee of one of the ministry's innumerable advisory bodies draws up five-year plans. But, in effect, the budget is divided among researchers and institutions in the same proportions each year. The public, and even public officials, remain largely unaware that Japan's scientists are debating whether prediction is impossible or merely difficult. Most citizens do not realise that Tokai is the only region in which the government even intends to attempt a short-term warning. High public expectations are coming back to haunt the six-member panel of experts, which must conclude that the gathered data indicate either 'a cause for concern' or 'no cause for concern'. Mogi would like to add a third category between the two that would indicate 'some level of concern'. Many scientists agree a 'maybe' is not unreasonable, given the state of the art. Public officials, however, are insisting the experts make an 'it's coming' or 'it's not' decision. Meanwhile, the controversy might be settled if the experts get their call from the technicians monitoring the Tokai data.
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