Could the animals in our lives provide an early warning of earthquakes?
Reports have appeared for years about unusual behaviors in animals such as horses, dogs, cats, cows and sheep ahead of major earthquakes.
Even though scientists cannot reliably predict when and where an earthquake will occur, the question of whether animals can provide a suitable early warning system has been investigated in little detail.
To learn more, researchers from the Max Planck Institute of Animal Behavior and the University of Konstanz, both in Germany, joined forces to investigate whether cows, sheep, and dogs can detect early signs of earthquakes.
They attached sensors to the animals in an earthquake-prone area in Northern Italy and recorded their movements over several months.
The information they gathered showed that the animals were unusually restless in the hours before earthquakes.
The closer the animals were to the epicentre of the impending quake, the earlier they started behaving unusually.
The movement profiles of different animal species in different regions could, therefore, provide clues about the location and time of an impending earthquake, the researchers said.
Experts disagree about whether earthquakes can be exactly predicted. Nevertheless, animals seem to sense the impending danger hours in advance.
For example, there are reports that wild animals leave their sleeping and nesting places immediately before strong quakes and that pets become restless.
However, these anecdotal accounts often do not stand up to scientific scrutiny because the definition of unusual behaviour is often too unclear and the observation period too short. Other factors could also explain their behaviour.
In order to be able to use animal activity patterns as a kind of early warning system for earthquakes, the animals would have to show measurable behavioural changes. And if they do indeed react to weak physical changes immediately before an earthquake, they should react more strongly the closer they are to the epicentre of the quake.
The animals used for the study were on a farm. The researchers, whose findings are reported in the journal Ethology, attached accelerometers to the collars of six cows, five sheep, and two dogs that had already displayed unusual behaviour before earthquakes.
The researchers then recorded their movements continuously over several months. During this period, official authorities reported about 18,000 earthquakes in the region.
In addition to many small and hardly noticeable quakes, there were also 12 earthquakes with a strength of 4 or higher on the Richter scale.
The researchers then selected the quakes that triggered statistically relevant earth movements on the farm. These included strong quakes up to 28km away, as well as weaker quakes, the epicentres of which were very close to the farm.
However, instead of explicitly looking for abnormal behaviours in the period before these events, the researchers chose a more cautious approach. They first marked all behavioural changes of the animals that were unusual according to objective, statistical criteria.
“In this way, we ensure that we not only establish correlations retrospectively but also that we really do have a model that can be used for predictions,” explains Professor Martin Wikelski, director at the Max Planck Institute of Animal Behavior and principal investigator at the Centre for the Advanced Study of Collective Behaviour.
The data – measured as the body acceleration of each farm animal (indicating activity level) – were evaluated using statistical models drawn from financial econometrics.
“Because every animal reacts differently in size, speed and according to species, the animal data resemble data on heterogenous financial investors,” explains co-author Winfried Pohlmeier, Professor of Econometrics at the University of Konstanz and Principal Investigator at the Centre for the Advanced Study of Collective Behaviour.
The scientists also considered other disturbance factors such as natural changes in animal activity patterns over the day.
In this way, the researchers discovered unusual behavioural patterns up to 20 hours before an earthquake.
“The closer the animals were to the epicentre of the impending shock, the earlier they changed their behaviour. This is exactly what you would expect when physical changes occur more frequently at the epicentre of the impending earthquake and become weaker with increasing distance,” explains Wikelski.
However, this effect was clear only when the researchers looked at all animals together.
“Collectively, the animals seem to show abilities that are not so easily recognized on an individual level,” Wikelski says.
It is still unclear how animals can sense impending earthquakes. Animals may sense the ionization of the air caused by the large rock pressures in earthquake zones with their hair. It is also conceivable that animals can smell gases released from quartz crystals before an earthquake.
Earthquake early-warning system
Real-time data measured by the researchers and recorded since December 2019 show what an animal earthquake early-warning system could look like: a chip on the collar sends the movement data to a central computer every three minutes. This triggers a warning signal if it registers a significantly increased activity of the animals for at least 45 minutes.
The researchers received one such warning. “Three hours later, a small quake shook the region,” says Wikelski. “The epicentre was directly below the stables of the animals.”
However, before the behaviour of animals can be used to predict earthquakes, researchers need to observe a larger number of animals over longer periods of time in different earthquake zones around the world.
For this, they want to use the global animal observation system ICARUS on the International Space Station, which will start its scientific operation in a few weeks.
ICARUS, a scientific project directed by Martin Wikelski, is a joint project funded and carried out by the German Aerospace Center and the Russian space agency Roskosmos. It is supported by the European Space Agency.
Martin Wikelski, Uschi Mueller, Paola Scocco, Andrea Catorci, Lev Desinov, Mikhail Belyaev, Daniel Keim, Winfried Pohlmeier, Gerhard Fechteler, P. Martin Mai “Potential short-term earthquake forecasting by farm-animal monitoring”, Ethology, 3 July 2020.