How animals predict earthquakes
Baku, December 2 (AZERTAC). Animals may sense chemical changes in groundwater that occur when an earthquake is about to strike. This, scientists say, could be the cause of bizarre earthquake-associated animal behaviour. Researchers began to investigate these chemical effects after seeing a colony of toads abandon its pond in L`Aquila, Italy, in 2009 - days before a quake. They suggest that animal behaviour could be incorporated into earthquake forecasting. The team`s findings are published in the International Journal of Environmental Research and Public Health. In this paper, they describe a mechanism whereby stressed rocks in the Earth`s crust release charged particles that react with the groundwater. Animals that live in or near groundwater are highly sensitive to any changes in its chemistry, so they might sense this days before the rocks finally "slip" and cause a quake. The team, led by Friedemann Freund from Nasa and Rachel Grant from the UK`s Open University hope their hypothesis will inspire biologists and geologists to work together, to find out exactly how animals might help us recognise some of the elusive signs of an imminent earthquake. The L`Aquila toads are not the first example of strange animal behaviour before a major seismic event. There have been reports throughout history of reptiles, amphibians and fish behaving in unusual ways just before an earthquake struck. In 1975, in Haicheng, China, for example, many people spotted snakes emerging from their burrows a month before the city was hit by a large earthquake. This was particularly odd, because it occurred during the winter. The snakes were in the middle of their annual hibernation, and with temperatures well below freezing, venturing outside was suicide for the cold-blooded reptiles. But each of these cases - of waking reptiles, fleeing amphibians or deep-sea fish rising to the surface - has been an individual anecdote. And major earthquakes are so rare that the events surrounding them are almost impossible to study in detail. This is where the case of the L`Aquila toads was different. Ms Grant, a biologist from the Open University, was monitoring the toad colony as part of her PhD project. "It was very dramatic," she recalled. "It went from 96 toads to almost zero over three days." Ms Grant published her observations in the Journal of Zoology. "After that, I was contacted by Nasa," she told BBC Nature. Scientists at the US space agency had been studying the chemical changes that occur when rocks are under extreme stress. They wondered if these changes were linked to the mass exodus of the toads. Their laboratory-based tests have now revealed, not only that these changes could be connected, but that the Earth`s crust could directly affect the chemistry of the pond that the toads were living and breeding in at the time. But, Dr Grant says this is the first convincing possible mechanism for a "pre-earthquake cue" that aquatic, semi-aquatic and burrowing animals might be able to sense and respond to. "When you think of all of the many things that are happening to these rocks, it would be weird if the animals weren`t affected in some way," she said. Dr Freund said that the behaviour of animals could be one of a number of connected events that might forecast an earthquake. "Once we understand how all of these signals are connected," he told BBC Nature, "if we see four of five signals all pointing in the same direction, we can say, `ok, something is about to happen`."
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