The notion that animals can “predict” earthquakes dates back to 373BC, when the Greek historian Thucydides wrote of rats, snakes, dogs, and weasels fleeing the city of Helice just days before a catastrophic earthquake. In the modern world, there are still anecdotes of peculiar animal behavior hours and even days before a quake. Whilst most tales do not stand up to scientific scrutiny, an international team of researchers wanted to investigate whether some farm animals could serve as an early warning system for earthquakes.
For the experiment, the team focused on an earthquake-prone area in Northern Italy. They attached sensors to six cows, five sheep, and two dogs already known for their “sixth sense,” and recorded their movements over several months. Where anecdotes usually fall down is in the vague description of the animal’s unusual behavior and whether it could be attributed to a different factor. Therefore, to make their observations watertight, the team recorded abnormal behavior in line with objective, statistical criteria, and did so for all occurrences, whether they were before an earthquake or not.
“In this way, we ensure that we not only establish correlations retrospectively but also that we really do have a model that can be used for predictions,” Martin Wikelski, director at the Max Planck Institute of Animal Behavior, Germany, and co-author of the study published in Ethology: International Journal of Behavioural Biology, said in a statement.
From the animal’s activity data gathered by the sensors, Wikelski and the team discovered unusual behavior patterns up to 20 hours before an earthquake. In fact, the closer the animals were to the quake’s epicenter, the earlier their restless behavior began, adding further fuel to the hypothesis being tested.
“This [behavior] is exactly what you would expect when physical changes occur more frequently at the epicenter of the impending earthquake and become weaker with increasing distance,” Wikelski explained. Although, Wikelski continued, the pattern only emerged when looking at the farm group as a whole, and “not so easily recognized on an individual basis.”
Nobody can yet reliably predict when and where an earthquake will occur, in part because seismologists can’t seem to find any signals from Earth that consistently precede a quake. In this vein, the reason for animal’s apparent detection abilities is still unclear. Some suggest that animals use their fur to sense the ionization of air, caused by heightened rock pressures in earthquake zones; others propose that animals can smell gases released from quartz crystals prior to a quake.
In the absence of an answer, it is still a jump to say that animals can “predict” an earthquake. However, by scaling up their observations to encompass more animals over longer periods of time across earthquake zones around the world, the team believe they may be able to create an “earthquake early warning system.”
Indeed, they have already trialed one with the original farm group where an alert was sounded if the animals’ activity was raised for at least 45 minutes. After one such warning was received from the system, “three hours later, a small quake shook the region,” Wikelski recalled. “The epicenter was directly below the stables of the animals.”
Time will tell whether animal’s apparent “sixth sense” has legs.