Seismic early warningsAnimals have built-in seismic early-warning mechanism: Scientists

Unusual animal behaviors (UABs) have been observed before large natural disasters including earthquakes, but these animals’ “early warning” mechanisms have not been scientifically identified. A recent study in Japan investigated the behaviors of cats and dogs, and changes in dairy milk production, before the magnitude-9.0 earthquake that struck the island nation on 11 March 2011. Following the earthquake and tsunami, scientists led by Hiroyuki Yamaguchi conducted a nationwide study in December 2011 and January 2012, surveying more than 1,200 dog owners living between 140 kilometers to 2,350 kilometers away from the epicenter ,and 703 cat owners living up to 1,950 kilometers away from the epicenter. Pet owners were asked whether they recognized unusual behaviors in the minutes, hours, and days prior to the earthquake. Unusual behaviors included howling and barking (for dogs), vocalizing (for cats), trembling, being restless, and escaping.

Scientists also examined the amount of milk produced daily from 1 January 2011 until 31 March 2011 by cows in three different locations: Ibaraki Prefecture (340 kilometers from the epicenter), and at Kanagawa and Shizuoka Prefectures (both further away). Yamaguchi believes that if cows are able to predict an earthquake, they will become stressed and produce less milk. The study also took into consideration the length of time since calving and the temperature and humidity, as these factors are known to affect milk yield.

Pacific Standard Magazinereportsthat the study showed that unexpected behaviors were reported by 19.7 percent of dog owners and 16.4 percent of cat owners. Sixty percent of dog owners who reported unusual behaviors said they recognized the behaviors within seconds and minutes before the quake struck. Roughly 17 percent of dog owners observed unusual behaviors a few hours before the quake. In cats which showed unusual behaviors, 45 percent showed it immediately, and 30 percent showed it in the few hours before the earthquake. Six percent of dog and 3 percent of cat owners observed unusual behaviors six or more days before the quake.

According to the research studypublished in Biological Anomalies Prior to Earthquakes, animals might detect earthquakes for several reasons, including that cats and dogs have a wider hearing range and better scent detection than humans. “Possible candidate stimuli,” the researchers wrote, “include changes in atmospheric pressure, changes in gravity, ground deformation (ground uplift and tilt changes), acoustic signals and vibrations due to the generation of micro cracks, groundwater level changes, and emanations of gases and chemical substances.”

Yamaguchi acknowledges that the fault with surveys post-event is that participants may have forgotten exactly what occurred; therefore the examination of milk production could help shed better light on the subject matter. In Kanagawa and Shizuoka Prefectures, further from the epicenter, dairy facilities recorded no changes in milk production in the days leading up to the quake, but in Ibaraki, dairy cows produced significantly less milk on 11 February, and on the 5th, 6th, 7th, and 8th days of March. “The facility in Ibaraki showed lowered milk production 6 days before the EQ (earthquake),” the researchers wrote. “The decrease in milk yield continued for four days. This might be because Ibaraki was the closest of the three institutes to the epicenter. If so, milk yield might be useful as an EQ precursor.” Yamaguchi concluded that the UABs observed could contribute to the prediction of earthquakes but “but the longitudinal and objective measurement of UABs and the verification of the relevance between milk yield levels and other earthquakes need to be performed.”