Can animals warn about earthquakes? This question has been argued for decades. On the one hand there are numerous reports of chickens, sheep or dogs that behaved strangely before a quake. On the other hand, there are many earthquakes before which such abnormal animal behavior has precisely not been observed. Moreover: The exact time of such an event depends on many different factors and can probably never be accurately predicted according to the current state of science. So how should ordinary domestic and wild animals be in a position to do so?
Scientists at the GFZ German Research Center for Geosciences in Potsdam had a closer look at the available data. "The reports of conspicuous behavior are numerous, but it could have other causes," says Heiko Woith. "We have looked more closely at such studies and investigated whether there is a statistical correlation between seismic activity and animal behavior." This first comprehensive statistical analysis is published in the journal Bulletin of the Seismological Society of America.
The analysis included more than 700 records of claimed animal precursors related to 160 earthquakes with unusual behavior of more than 130 species - from sheep to goats to snakes and fish. The reports come from two dozen countries, most of them from New Zealand, Japan, Italy and Taiwan.
Among other things, Woith's team has investigated the effect of foreshocks: noticeable vibrations, which occur on every tenth earthquake days or even weeks before. They used data from an earthquake catalog (ISC-GEM), which records worldwide earthquakes of magnitude M 5.6 and higher in the years 2000-2012. "We have assumed that such vibrations are felt at a distance of 100 kilometers for animals," says Woith. "Then we have examined for all earthquakes from magnitude six or higher, whether there were foreshocks in this area within 60 days." The result: 16 percent of the main shocks were preceded by such foreshocks within 60 days; whereas only 7 percent (three percent) of the main shocks were preceded by foreshocks within one day (one hour). "The temporal clustering is similar to the observed one for animal precursors," says Woith. "We suggest that at least part of the reported animal precursors is in fact related to foreshocks."
However, further statements are very difficult. One reason is that the data is very heterogeneous. The described observations are often anecdotal and unsuitable for sound scientific investigation. In addition, other relationships between earthquakes and the behavior of animals are discussed, for example, as a reaction to degassing. "One has to keep in mind that a number of earthquakes are not announced by degassing or other signs, but literally occur spontaneously," adds the GFZ researcher. Nevertheless, it was an interesting research question, if animals could be used as earthquake detectors. However, according to the current state of science, the chances of success are not too great, says Woith: "An accurate prediction of the location, magnitude and time of a quake seems, according to everything we know, to be impossible. And a reliable early warning on the basis of foreshocks or release of gases from the ground has many uncertainties and has, so far, not succeeded even with the most modern sensors. "
Original study: Woith, H., Petersen, G.M., Hainzl, S., Dahm, T., 2018. Can Animals Predict Earthquakes? Bulletin of the Seismological Society of America. DOI: https://doi.org/10.1785/0120170313