Nature provides pre-earthquake cues

The earth provides early warning signs of impending quakes say two groups of researchers who have been studying ozone emissions from fracturing rocks, and a colony of toads.

Dr Rachel Grant and Dr Friedemann Freund have uncovered a mechanism whereby stressed rocks in the Earth’s crust release charged particles that react with groundwater. Animals living in or near this water are highly sensitive to any chemical changes, and may sense this before the rocks actually slip

Grant believes this caused a colony of toads she was studying as part of her PhD to abandon the pond they were living and breeding in just before the 2009 L’Aquila earthquake in Italy.

“It was very dramatic,” she said. “It went from 96 toads to almost zero over three days.”

The chemical chain of events could affect the organic material dissolved in the pond water, turning it into substances toxic to aquatic animals. The pair says the mechanism is complicated and needs thorough testing. They hope their work will inspire biologists and geologists to find out exactly how animals might help us predict imminent earthquakes

“When you think of all the many things that are happening to these rocks, it would be weird if the animals weren’t affected in some way,” said Freund, a NASA scientist.

Meanwhile, University of Virginia researchers – also investigating anecdotal evidence of animals anticipating earthquakes – believe changing levels of ozone could be another pre-earthquake signal.

Raúl Baragiola, a professor of engineering, realised that if animals were sensitive to chemical changes, then a series of ozone detectors might indicate seismic activity.

They devised a series of experiments to distinguish exactly where the gas came from – the rocks or reactions in the atmosphere – and discovered ozone was produced by fracturing rocks in conditions containing oxygen. This indicates it came from reactions in the gas and that rock fractures may be detectable by measuring ozone.

“If future research shows a positive correlation between ground-level ozone near geological faults and earthquakes, an array of interconnected ozone detectors could monitor anomalous patterns when rock fracture induces the release of ozone from underground and surface cracks,” said Baragiola.

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