Toads Detect Silent But Deadly Pre-Earthquake Gas
Dec 5th 2011Stories of animal behavior changing in advance of earthquakes dates back centuries, but now scientists have some clues why that might be, at least with amphibians. Days before a big quake in Italy in 2009, the population of a breeding pond of toads went from 96 to zero. Researchers found that rocks under great stress, such as immediately before tectonic plates shift, release charged particles that can flow through soil until they make contact with air, where ions are created. Positive airborne ions cause headaches and nausea in humans and increase serotonin, a stress hormone, in animals; said the lead scientist, who speculates that the changing underground chemistry could be toxic for the toads.