
It is often believed that animals can predict earthquakes and other disasters. But is it proven? And what is the real impact of such disasters as earthquakes or tsunamis on wildlife and domestic animals?
Some historical facts
The earliest animal behavior before an earthquake was recorded by historians in the Greek city of Helike in 373 BC. The animals initially behaved unusually, followed by their large migration. The inhabitants thought that animals were fleeing en masse from danger, and two days later, the region experienced some of the strongest tremors in its history.
In Haicheng, China dozens of snakes left their burrows despite intense cold several days before a 7.3 magnitude earthquake hit the city on February 4, 1975. The behavior of the reptiles, as well as other incidents, helped convince the authorities to evacuate the city several hours before the catastrophic events, avoiding mass casualties among the population.
Thanks to eyewitnesses, there is a lot of information that on the eve of earthquakes, animals and birds begin to behave restlessly, leave nests, safe nighttime shelters and try to move away from the site of a potential disaster. How can animals sense impending events if scientists have not yet found a way to detect an approaching disaster?
How animals predict earthquakes
Specialists do not conduct systematic observations of animals behaving strangely or leaving the area before an earthquake. Although there is a lot of unofficial evidence of such phenomena. Therefore, there are no official scientific explanations regarding the senses (smell, touch, hearing) through which wild and domestic animals can predict earthquakes in advance.
It is believed that some animals, thanks to their acute senses, can detect vibrations in the ground a few minutes before an earthquake. During an earthquake, two types of energy waves are generated in the Earth’s crust. A small P-wave (compressional wave) appears shortly before the main events. It comes just before the large S-wave (shear wave). The P-wave can pass through materials with different densities. Therefore, the P-wave travels faster than the S- wave, which passes only through solids and is responsible for the vibrations during an earthquake.
Few people are sensitive to P-wave vibrations, whereas animals can detect them quite easily. It is the peak values of the P-wave that cause animals to behave restlessly and migrate from their habitats to safe regions. Despite this, P-wave detection allows to sense an earthquake a few seconds or minutes before its occurrence. But many animals change behavior several hours or even days before an earthquake.
Opinions of scientists
In a joint study by the Max Planck Institute and the University of Konstanz in Germany, researchers have found that domestic animals can detect the first signs of an impending earthquake many hours before. They attached sensors to animals in a seismically active area in Northern Italy and tracked their movements for six months.
The data showed that animals began to exhibit signs of anxiety approximately 20 hours before the disaster. And the closer they were to the epicenter of the impending event, the faster they began to behave unusually.
Experts disagree on how animals can sense an earthquake. Some experts believe that:
- animals’ sense mechanical vibrations from processes occurring in the Earth’s crust;
- some animals, thanks to their fur and feathers, sense air ionization caused by the pressure of large rocks in areas of potential earthquakes. The moving tectonic plates press on rocks along the fault line several days before an earthquake. As a result of this, minerals are released from the rock, emitting ions into the atmosphere;
- animals are more sensitive to sudden changes in electromagnetic fields that occur before an earthquake, both in the soil and in the atmosphere;
- many birds and animals can sense changes in the gas environment that occur during disasters.
Scientists plan to make systematic observations of many different breeds to conduct extensive studies of animal behavior for earthquake prediction. For this purpose, it is planned to use the global animal observation system ICARUS on the International Space Station.
Researchers around the world are developing new projects to determine whether animals are sensitive to seismic activity. This could help create early earthquake detection tools to protect the lives and property of people living in earthquake-prone regions.