Earthquakes sensed by animals before they strike

Weeks before earthquakes strike, wild animals have the ability to sense their imminent arrival and move about much less, researchers from the UK, US and Brazil reported this week.

They suggest motion-activated cameras could be used to monitor animal movements in areas of high seismic activity as an early-warning system.

The researchers explained in the academic journal Physics and Chemistry of the Earth (citation below) that reports on pre-earthquake changes in animal behaviour have generally been greeted with skepticism by scientists, because most of them have been anecdotal by nature with very little scientific evidence regarding their possible causal mechanisms.

The motion-triggered cameras were placed in The Yanachaga–Chemillén National Park (Parque Nacional Yanachaga-Chemillén), located in the Pasco Region in Peru.

According to the US Geological Survey (USGS), references of animals behaving abnormally prior to a significant earthquake date back to Greece in 373 BC. Centipedes, snakes, weasels and rats reportedly left their homes and headed to safety many days before a destructive earthquake.

In this latest study, led by Rachel Grant, a lecturer in Animal and Environmental Biology at Anglia Ruskin University in England, the scientists monitored the activities of wild animals over a 30-day period with motion-triggered cameras at the Yanachaga National Park in Peru, just before the 2011 magnitude 7.0 Contamana earthquake.

Animals moved about less before the earthquake

They found that animal activity declined considerably during the 3-week period before the earthquake struck, compared to periods of low-seismic activity.

In five of the last seven days before the Contamana earthquake, the motion cameras picked up no animal movements at all, which is extremely unusual for wildlife in this mountainous rainforest region, the authors explained.

Prof. Grant said theirs was the first study to scientifically document a decline in animal movements before an earthquake.

In an interview with Reuters, Prof. Grant said:

“Animals have the potential to be reliable forecasters of earthquakes and could be used alongside other monitoring systems. The system could be used in developing and earthquake-prone countries, it is affordable and feasible to implement as it just requires someone to monitor animal behaviour… there is no need for satellites.”

Atmospheric fluctuations before the quake

Two weeks before the quake, scientists detected changes in the atmosphere that originated from the Earth’s surface as pressure was building up.

These changes can trigger spikes in blood serotonin levels in animals, including humans, making them agitated, hyperactive and restless, the authors wrote.

Eight days before Contamana struck, their sensors recorded a large fluctuation in the atmosphere surrounding the epicenter, which coincided with a significant reduction in animal activity.

All the rainforest’s wildlife were affected by the change in the atmosphere, with rodents seemingly the most sensitive to seismic movements, the researchers said.

Animals, with their heightened sensitivity to subtle changes that may occur during the days leading up to an earthquake, may help give scientists insight into what is going on, the authors believe.

Reuters quoted co-author Friedemann Freund, from the Department of Physics at San Jose State University, California, who is also a senior SETI scientist, who said:

“With their acute ability to sense their environment, animals can help us understand subtle changes that occur before major earthquakes.”

“These changes, that we are now able to measure, express themselves in many different ways at the earth’s surface and above.”

Citation: “Changes in Animal Activity Prior to a Major (M=7) Earthquake in the Peruvian Andes,” Rachel A. Grant, Jean Pierre Raulin, Friedemann T. Freund. Physics and Chemistry of the Earth. Published online March 17, 2015.