Taipei 101, currently the world's tallest building, is being fitted with earthquake sensors at different heights to register any swaying. Movement during quakes is not necessarily greatest at the top of tall structures. The direction the shock comes from, the nature of the ground and the way the building was constructed all play their part. Earthquakes are a fact of life in Taiwan. Hardly a week passes without stirrings being recorded deep off the east coast, although only about four a year are felt by Taipei's citizens. But the island's September 1999 quake killed more than 2,400; while even more perished in a comparable event in 1935, and more than 1,000 died in 1906. Nevertheless, Taiwan is a near-perfect earthquake laboratory. It has the world's greatest concentration of seismic monitors, and more information was gathered about the 1999 disaster than on any previous quake anywhere. The subject does not lack academic enthusiasts. At the Seismology Centre of the Central Weather Bureau, scientists point out that although they monitor a variety of measurements taken throughout the island, they cannot officially subscribe to the theories underpinning all of them. One university professor, for instance, is looking at correlations between Taiwan's earthquakes and activity in the ionosphere. Sceptics might retort that mankind has been looking to the stars for centuries in an attempt to predict the future. But the research looks only at quake activity at Taiwan's precise latitude, and besides, the professor has said, possible precursors and exact predictions are very different things. Elsewhere, readings from 120 Global Positioning System monitors (with 30 more soon to be added) are constantly relayed to the Central Weather Bureau. If Taiwan's land surface is shifting, even minutely, the bureau's seismologists immediately know about it. One service the Seismological Centre performs is to automatically alert organisations such as the subway (MRT) and banks to major movements elsewhere on the island. Shock waves due to reach the capital in, say, 40 seconds are thus briefly anticipated. Computers automatically halt MRT trains, suspend bank cash-machine operations, and alert gas suppliers. Precise prediction, nevertheless, continues to evade human ingenuity, in Taiwan as elsewhere. The only known case of warnings being issued, buildings evacuated, and an earthquake following within the hour was in Haicheng, in China, in 1975. Even here, the facts are disputed. The truth is that earthquakes remain stubbornly unpredictable. The only recourse, therefore, lies in safer buildings.