There is a huge amount of anecdotal evidence regarding abnormal behaviour displayed in animals prior to the occurrence of an earthquake, going all the way back to Ancient Greece in 373 BC, when snakes, rats and weasels were reported to vacate the Greek city of Helice days before an earthquake devastated the area. Reports of cats, dogs and a wide variety of animals acting strangely prior to an earthquake have abounded in recent years, and if the study of animal behaviour could be used in the prediction of quakes it would be of immensely valuable use in the reduction of human life lost when destructive earthquakes occur. For all the advances in modern technology made in the last 100 years, earthquakes still remain incredibly hard to predict.
As well as plentiful reports of domestic animals acting strangely prior to a quake, there have been several interesting documentations of strange animal behaviour of more biblical proportions preceding an earthquake. In 2009, a research team studying the mating behaviour of the common toad (Bufo bufo) in L’Aquila, Italy, reported that 5 days prior to a quake measuring 5.8 on the richter scale, the activity of male toads in the region declined by about 96%. This pattern persisted until ten days after the earthquake struck, leading the team to propose that perhaps the toads could sense some change in the ionosphere which led to a change in their behaviour and subsequent transit from the site.
Another report of an earthquake related toad exodus occurred prior to the deadliest earthquake of the last century, the 1976 Tangshan earthquake in China, which killed upwards of 240,000 people. Three days prior to the quake, thousands of toads were seen on the streets of Mianzhu, a city hard hit by the natural disaster. There also reports of a mass exodus for higher ground undertaken by elephants and other large mammals after the 2004 Tsunami on the island of Sri Lanka.
In fact, elephants pop up rather frequently in the literature on strange animal behaviour prior to and immediately after earthquakes, and it is thought that they can perhaps detect seismological alterations in the earths crust at a far more sensitive level than humans. They are known to communicate using frequencies too low to be audible to the human ear, and it is possible that this sensitivity to low frequencies could be of use to them in predicting earthquakes.
It all would seem to be quite encouraging in terms of adding another factor to the list of processes that could help determine the occurrence of an earthquake, but the major problem is that any anecdotal evidence on the matter could be clouded by the benefit of hindsight. It is usually only after an earthquake occurs that the any strange animal behaviour will be linked to it and efforts to predict earthquakes in China and Japan using changes in animal behaviour have proven to be erratic at best. There are so many factors that can determine the behaviour of an animal or group of animals that it’s often all too simple and misleading to conclude that any abnormalities are a result of seismic activity. What’s missing from the equation is objective data.
There have been few objective studies on this topic, a fact not helped by the impossibility of knowing when and where an earthquake will occur, as well as the lack of knowledge pertaining to what behaviours to look for and in what species in such a situation. In 2008 a team of researchers from the University of Sichuan, China, undertook a study monitoring locomotor activity in mice over a period during which a magnitude 8.0 earthquake struck in Wenchuan County. They found that the locomotor activity in six of the eight mice studied underwent a dramatic increase three days prior to the quake and stayed that way until three days after. Evidence such as this is low on the ground, and the cues picked up by any animals thought to change behaviour as a result of seismic activity are also extremely hard to determine.
Whether animals can predict earthquakes remains a divisive topic to seismologists and researchers in the biological sciences. It seems like a subject area that will be driven by anecdotal evidence for a long time to come. This is a shame, as even if it proves to be unfounded, its research would no doubt produce a lot of valuable data on animal behaviour, and if there is something in the old wives tale, then anything that helps toward reducing the loss of life caused by earthquakes can only be a good thing.
By Ben Margerison