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Researchers have come up with a new way of tracking elephants, via the vibrations that the animals make.

Scientists Dr Beth Mortimer and Prof Tarje Nissen-Meyer discovered that elephants generate vibrations through their normal movements and through vocalisations, known as "rumbles".

These can be measured by techniques usually used for studying earthquakes.

The Oxford academics spoke about their research at the TEDWomen conference currently under way in California.

They explained how they measured the seismic waves that could travel nearly four miles through the ground.

They recorded the vibrations generated by wild elephants in Kenya while walking and calling, using instruments known as geophones.

Seismological modelling software that incorporates the local geological information was combined with computer algorithms to produce accurate estimates of the seismic waves produced by elephants.

They filmed the animals during recordings and later synchronised the two to allow them to visually confirm that the vibrations originated from elephants.

They found that other noise and soil type affected their ability to distinguish the patterns over long distances. Vibrations travel farther through sand than through hard rock and also when little other noise is present to interfere.

Finding out what elephants are doing, even when they are some distance away, could help fight poaching in real time as well as offering insights into their behaviour, they said.

for journal Current Biology earlier this year.

Save The Elephants' chief executive, Frank Pope said of the research: "Legends and folklore have long spoken about the way elephants cannot only communicate across long distances, but also detect other events that shake the ground like far-off thunder.

"This study marks a new phase in trying to understand the nature of the vibrations elephants produce and how they might be used by elephants themselves.

"Along the way it is opening our eyes to the challenges posed by human-generated noise in an increasingly crowded landscape."