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Trickle of hope

发布时间:2019-03-07 02:04:02来源:未知点击:

By Padma Tata and Nicola Jones Water has suddenly appeared in the middle of an arid part of north-west India, as a result of January’s devastating earthquake in Gujarat. As many as 20,000 people may have died in the magnitude 7.7 tremor. The water is the one small ray of hope to have come out of the devastation. The new watercourses appeared after the earthquake liquefied the clay and sand in ancient river beds. Underground water quickly rose to the surface to flood the channels. The region is regularly convulsed by earthquakes. “The Indian plate is colliding with the Asian plate, so the land is crumpling up, says Roger Musson of the British Geological Survey in Edinburgh. Over the years these earthquakes have diverted watercourses and dried up rivers, turning the lush grassland of thousands of years ago into a barren wasteland. Local geologists hope the latest earthquake may help to reverse the process. None of these channels was visible on images taken immediately before the earthquake. Eyewitness reports say two-metre-high fountains of water appeared near Bhachau, a town that was totally destroyed by the earthquake. Describing the appearance of the river channels as “the only silver lining” in the devastation, Janardhan Negi of the Geophysical Research Institute in Hyderabad, said the channels could belong to either or both of two ancient rivers in north India. One is the semi-mythical Saraswati, which legend says dried up 4000 years ago. Satellite images have found underground channels in areas where the Saraswati is supposed to have flowed. The second is part of the river Indus, which was diverted after a violent earthquake in 1819. Negi says the 1819 earthquake created a 100-kilometre-long fissure that diverted the river. As the Indus delta dried out and sank, the sea flooded 4500 square kilometres of the delta, before drying out to leave behind vast salty stretches. However, the new channels will not make the old lost rivers flow again. Tests have shown that the water is saline. “The feeder for the rivers cannot be located,” says Negi. But the channels may alter the water drainage pattern in the dry area and help to rejuvenate it, he said. Roger Bilham, a geologist from the University of Colorado, whose colleagues have just returned from the earthquake zone, is also sceptical. “The rivers are draining a river catchment,