Predicting earthquakeDoes toad behavior predict earthquakes?
Italian researchers studying toads’ mating habits noticed that a large number of toads left L’Aquila province of Italy a few days before it was hit with a devastating earthquake last April; the researchers suggest that toads sense changes in radiation emitted from Earth’s ionosphere, changes which typically precede earthquakes; other researchers say: not so fast
Last spring, a group of biologists were studying the mating habits of the common toad (Bufo bufo) in the L’Aquila province of Italy. As temperatures warm each year, male toads gather en masse at small ponds to compete for the affections of females. As part of their study, the scientists ventured out to one particular pond every evening to count the toads and note whether they had laid any new eggs.
Discovery News’s Michael Reilly writes that a few days into their work, something strange happened: the toads scattered. Spawning had only just begun, and where there had been between 80 and 90 male toads for the last few days of March, the first few days of April turned up fewer than ten.
Then, on 6 April, a magnitude 6.3 earthquake hit, ravaging L’Aquila province and its capital city of the same name. Hundred of people were killed and thousands injured as buildings that dated to the middle ages crumbled.
In a new paper out this evening in Journal of Zoology, the researchers claim this sequence of events is more than just a coincidence. Toads stayed away from the pond for several more days following the quake, before finally returning in force around 15 April. No word on where the toads went, exactly, to flee the disaster. The question: did the toads sense the coming quake and headed for the hills? This is precisely what the researchers are arguing.
Reilly writes that there are many accounts of the planet showing signs an earthquake can be predicted — by increasing levels of radon in local waterways, changes in cloud pattern above a fault, fluctuations in very-low frequency radiation in the ionosphere — “and those are the semi-credible earthquake precursors,” he adds (see “Earthquakes Cannot Be Predicted with Accuracy, Say Seismologists,” 8 April 2009 HSNW).
The researchers admit they do not know what it was that tipped the toads off, but they offer several theories. One in particular is a series of measurements that suggest radiation emitted from Earth’s ionosphere was going haywire.
To examine the Italian researchers’ theories, Reilly consulted with Susan Hough, a seismologist at Caltech. After having a read of the paper, here are her comments:
This is a good example of bad science. The earthquake prediction heyday of the 1970s was launched and sustained by similar studies: people who found snippets of data after the fact that showed an apparent correlation between some signal and an eventual earthquake. This is not good statistics. You can’t select data after the fact.
In this case, there’s no way to know what kind of fluctuations are normally seen in toad activity, or what else might have been going on in the study area that could have influenced toad behavior.
It is within the realm of possibility that there are precursory signals before some earthquakes, and that animals might respond to them. But to demonstrate a significant correlation one would need to have a long record of objectively-recorded data before and after many earthquakes.
On the question of the ionosphere, she added:
There have been a number of studies of satellite observations that approach the bar for good science, in terms of applying rigorous statistics, etc. And, again, it is within the realm of possibility that VLF [Very Low Frequency] precursors exist.
But the snippets of data shown are insufficient to draw conclusions.
…
There are really two questions: 1) do precursors exist, and 2) do useful precursors exist? It is possible that precursory signals — electromagnetic, whatever — are generated in the earth prior to SOME earthquakes, but these precursors, if they exist, will have no predictive capability if they do not reliably occur before large earthquakes, and only before large earthquakes.
“I would love a future in which toads are prized for their earthquake-predicting prowess, and are kept in every apartment in Tokyo, Istanbul, Seattle, Los Angeles, and seismically active areas around the world as talismans to warn against impending doom,” Reilly writes. “But I am inclined to agree with Dr. Hough. For now at least, the hunt for a way to predict earthquakes must continue.”
