THE devastating earthquake that levelled parts of northern Pakistan and neighbouring Kashmir on 8 October came as no surprise to geologists. While the region is geologically active, it has suffered relatively few large earthquakes in the last century, leaving it primed for a big one.
As 快猫短视频 went to press, the quake had reportedly claimed more than 33,000 lives, and hopes of finding many more survivors were fading. The magnitude 7.6 earthquake struck at 0850 local time (0350 GMT), with the epicentre close to the city of Muzaffarabad and only 10 kilometres below the surface.
The affected region lies along the fault line where the northward-moving Indian tectonic plate plunges beneath the Eurasian plate, pushing up the Himalayan mountain range. Saturday鈥檚 earthquake was the most powerful along the fault since 1950.
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GPS measurements taken on opposite sides of the fault suggest that the plates are moving towards each other at a rate of around 2 centimetres a year. Records of earthquakes in the region examined in 2001 by Peter Molner and colleagues at the University of Colorado in Boulder showed that most of the stress built up by this convergence had not been released (Science, vol 293, p 1443). Particularly vulnerable were those parts of the fault where earthquakes had not occurred recently (see Graphic).
Earlier this year, Roger Bilham, also at the University of Colorado and Nicholas Ambraseys, an engineer at Imperial College London, predicted that the accumulated stress was equivalent to four quakes of magnitude 8.5 or larger (Current Science, vol 88, p 1658).
But it is impossible to predict the timing of such quakes. 鈥淐an we say, 鈥楾omorrow don鈥檛 go to school鈥�? No we are not at that stage,鈥� Molner says. However, knowing which areas face the greatest threat should help governments prepare, by building structures that can withstand an earthquake and educating people about the dangers.
There is a risk that last weekend鈥檚 quake will make other regions along the fault more prone to a slip, although again Molner says it is hard to make specific predictions. 鈥淭here is a possibility that the region between this earthquake and the one that occurred in 1905 would be at greater risk,鈥� he says.
