Science News

Toads tuned to earthquakes

Wed, 31st Mar 2010

Chris Smith

Toads may be able to predict forthcoming earthquakes, researchers speculate.

Geologists around the world have the electronic equivalent of a glass to the wall, listening to vibrations from inside the planet that herald the an Earthquake. But it turns out Toad cartoonthat they're not the only ones tuning in - toads do too!

In a paper published this week in the Journal of Zoology, Open University scientists Rachel Grant and Tim Halliday show some astonishing observations that reveal mating toads vanishing from an Italian lake 5 days before a major Earthquake struck.

The scientists were monitoring mating toads around the San Ruffino lake in central italy in the spring of 2009. These toads usually turn up together in large numbers, arrange their mating to coincide with the full moon and then remain in the vicinity until spawning is complete.

But on the 31st March, the 90 or so animals that had gathered to breed all abruptly vanished. Six days later the area was hit by a magnitude 6.3 Earthquake. Although a few toads returned at the full moon to mate, the majority remained AWOL in appreciable numbers for a further 9 days until after the last significant aftershocks had died away. Then their numbers climbed again.

Eliminating all other factors, the only explanation is that the toads somehow detected the impending Earthquake, five days ahead of its arrival. Incredible as this sounds, the results do resonate with other previous studies that have suggested that certain species might be able to predict when seismic upheavals are on the way.

In China scientists have described fish, rodents, wolves and snakes behaving oddly up to two months before a major quake in the 1970s and in Europe, Asia and the Americas researchers have also suggested that fish, rodents and some snakes seemed to be behaving oddly a week or so prior to a quake.

So the effect does appear to be real, and probably reflects a survival strategy on the part of the species concerned, but the big question is how are they doing this?

For now scientists don't know, but there are several possible ways it could happen. One is that they could be picking up on transient peaks in the levels of radon gas. This is a natural by-product of radioactive decay of uranium deep inside the Earth. When the Earth moves, trapped pockets of the gas can be released.

Another possibility is that local changes in the magnetic field could be upsetting the animals. If an impending upheaval alters the field, this could perturb behaviour. The effect could also reflect changes in the planet's ionosphere, the blanket of charged particles that envelopes the Earth out in space. There were perturbations in the ionosphere from 5 days prior to the Italian quake but quite how animals might pick up on this nobody knows.

But what is certainly true is that by hopping off five days in advance, even slow-moving toads have a chance to make it to safety!


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I think there are many anecdotes telling of animals fleeing the scene of a natural disaster before it happens. It was said that animals in Sri Lanka were noted to have moved inland before the 2003 tsunami struck.

Perhaps amphibians get even clearer signs of impending disaster due to water being such a good conductor of any tremors. Fish probably do too, but they can't run for the hills. Don_1, Mon, 5th Mar 2012

A tsunami, of course, can follow an earthquake, so running for the hills is a survival tactic, and certainly could be part of natural selection, especially on an island or peninsula. 

I would ask how dangerous quakes are to toads and their spawn.  Perhaps eggs or tadpoles get washed up on shore, or out to where they would become fish food, so spawning just before an earthquake would in fact pose a risk to the offspring.

Many large earthquakes are preceded by foreshocks.  I would have to ask about foreshocks for the Italian earthquake.  The problem is that the foreshocks are not very predictive of the large quakes magnitude, or timing.  However, again, if it was a survival issue, perhaps it could help disperse animals.

For example, the 2011 Japan earthquake was preceded by a magnitude 7.2 foreshock, which could easily have been interpreted as the main quake, followed by several strong aftershocks, but instead it was clearly a foreshock preceding a 9.0 quake a few days later.

CliffordK, Mon, 5th Mar 2012

So any good seismological station is going to need a bunch of wired-up toads as an early warning system. Goldfish would be cheaper. Couldn't they just transfer the genes? What would the transgenic creature be called? A goad? grizelda, Mon, 5th Mar 2012

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