The idea that animals can sense earthquakes is a popular one, and anecdotal stories about animals behaving strangely before major earthquakes have been told for centuries. However, debate over whether or not animals can truly sense earthquakes has not resolved the question, despite research in several earthquake-prone regions of the world. Some researchers believe that animals can, in fact, sense earthquakes, because they are more susceptible to subtle environmental changes than humans are. Others, however, argue that there are numerous causes for strange animal behavior, and that there many be a human psychological aspect involved in claims that animals can sense earthquakes.
Support for the idea that animals can sense earthquakes includes studies which suggest that animals may be able to sense vibrations before humans do. Animals have been proved to be more sensitive to ultrasonic waves such as the weaker p-waves which precede a major quake. It is possible that animals can sense an earthquake a few seconds before people do. In rare cases, an earthquake may be preceded by foreshocks, which may not be detectable by humans without specialized devices, but could be felt by animals. Other researchers have suggested that animals may sense chemical or electrical changes in the field of the Earth which could be indicators of an earthquake.
Other seismologists feel that there is no strong scientific evidence to support the idea that animals can sense earthquakes. They suggest that human psychology may be involved, as pet owners may want to attribute powers of premonition to their animals. The best way to conduct a study linking animal behavior with earthquake activity would be to have a hot line which pet owners can call to report odd behavior at any time, which seismologists could then link with actual earthquake data. Animal behaviorists have also pointed out that there are numerous causes for strange animal behavior, and that some pets may behave erratically before an earthquake, but for unrelated reasons.
Whether or not animals can detect earthquakes before humans do remains to be seen. In several earthquake regions outside of the United States, seismologists are attempting to establish strong scientific studies which could help to determine the level of animal sensitivity as part of a larger effort to learn how to predict earthquakes. For now, humans in earthquake regions should make sure that they have disaster kits on hand, and should look into more mundane causes for erratic animal behavior such as underlying medical conditions.