A new study suggests that toads, due to changes in their watery habitats,†may be able to detect pre-seismic clues to impending earthquakes. This comes after scientists observed a mass exodus of toads from one breeding ground just prior to the earthquake that struck the city of L’Aquila in Italy on 6 April 2009.
By serendipity Dr Rachel Grant of the UK’s Open University was in Italy at the time monitoring a toad population at San Ruffino Lake, around 74km from the 6.3 magnitude earthquake’s†epicenter.
During her observations Grant noted that five days prior to the earthquake the number of male common toads in the breeding colony fell dramatically, while three days prior to the earthquake most breeding pairs and males fled the site.
Grant speculated that the toads were leaving their aquatic habitats to find safer ground based on some kind of pre-seismic clues. But this left the question of precisely what triggered such behavior.
Grant duly published her observations in the Journal of Zoology. Shortly after, she was contacted by Nasa. The US space agency had at the time been studying the chemical changes that occur when rocks are put under extreme stress, and the scientists there had an inkling that their work might shed some light on the toads’†behavior.
Working with Nasa scientists, Grant has since used laboratory-based tests to theorize and support how the Earth’s crust may directly affect the chemistry of the pond the toads were living and breeding in, prompting the toads’ seeming ability to predict the earthquake.
Nasa geophysicist Friedemann Freund showed that, when rocks were under very high levels of stress – for example by the “gargantuan tectonic forces” just before an earthquake, they release charged particles.
These charged particles can flow out into the surrounding rocks, explained Dr Freund. And when they arrive at the Earth’s surface they react with the air – converting air molecules into charged particles known as ions.
“Positive airborne ions are known in the medical community to cause headaches and nausea in humans and to increase the level of serotonin, a stress hormone, in the blood of animals,” said Dr Freund. They can also react with water, turning it into hydrogen peroxide.
This chemical chain of events could affect the organic material dissolved in the pond water – turning harmless organic material into substances that are toxic to aquatic animals.
Hence why the toads would flee.
Researchers stress that these findings need further exploration, but Grant is optimistic that if verified these clues could be used to help predict an impending earthquake.
Dr Grant added: “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.
“Once we understand how all of these signals are connected, if we see four of five signals all pointing in [the same] direction, we can say, ‘OK, something is about to happen’.”
Any insight this or future studies might provide is particularly valuable given that predicting earthquakes is still something that is mostly beyond our current abilities.
The team’s findings are†published in the International Journal of Environmental Research and Public Health.
This is not the first time that animals have been thought to predict earthquakes of course.
Indeed the belief that animals are able to sense coming natural disasters has been around for centuries.
Most recently it was said that just before an earthquake struck America’s east cost earlier this year,†animals at National Zoo in Washington D.C began exhibiting unusual behavior such as odd vocalizations and a desire to hide themselves away.