Forecasting quakes

Toads, breaking rocks and ozone gas might hold the clue to predicting earthquakes in the future and enable the development of an advance warning system that could save many lives.

Seismic events often strike without warning, and that element of surprise makes them all the more deadly. Scientists have long looked for ways to predict them but have had little success, until recently.

But a team led by physicist Raul Baragiola of the University of Virginia has demonstrated that rocks crushed ahead of and during an earthquake produce ozone. In turn, the presence of ozone molecules near the earth's surface could explain a range of physical and animal phenomena anecdotally associated with the onset of a quake.

"There are these reports that may or may not be true that animals actually can detect [an earthquake] before it happens," said Raul Baragiola, a professor of engineering physics at the University of Virginia.

Accounts of bizarre animal behavior ahead of earthquakes date back to antiquity, but the unpredictability of quakes combined with the difficulty of simulating earthquake conditions in a laboratory setting has made formal research on the subject difficult.

A breakthrough came in 2009 when biologist Rachel A. Grant of the UK's Open University happened to be studying toad breeding colonies in Italy just before a 6.3-magnitude earthquake jolted an area northeast of Rome less than 100 km (62 miles) from where Grant was conducting her research.

Five days before the seismic event, almost all of the male toads abandoned the colony - a stark contrast with their normal behavior at the start of a breeding cycle. Three days before that, all breeding activity had stopped, and no new spawn was laid until nearly a week after the quake ended.

"Our findings suggest that toads are able to detect pre-seismic cues such as the release of gases and charged particles, and use these as a form of earthquake early-warning system," Grant told the BBC at the time of the study, adding that she was unsure what physical mechanism could explain the toads' behavior.

Parallel breakthroughs

Baragiola knew that animals seemed capable of predicting quakes, but he also knew that in the presence of sparks, oxygen gains an extra molecule and turns into ozone gas.

At certain levels, humans and animals may be sensitive to ozone's presence. People can often smell when lightning from a distant thunderstorm creates ozone.

Baragiola asked one of his students, Catherine Dukes, to test whether rocks, when breaking apart, create sparks that produce ozone. She began the series of experiments but crushing rocks slowly in a vice in small boxes and testing whether ozone was produced. It was.

The work done by the University of Virginia team and published in a November issue of Applied Physics Letters parallels findings published by Catherine Grant since her 2009 toad observations.

Earlier this year, Grant presented a paper in the International Journal of Environmental Research and Public Health in which she showed that pre-earthquake tectonic stresses activate electronic charge carriers underground.

Once those highly mobile carriers reach the Earth's surface, they create chemical conditions that can affect the groundwater, Grant claimed, turning normal water into hydrogen peroxide. That is one mechanism that could explain the toads' unusual decision to vacate the pool where they were breeding.

Seconds count

Ozone levels may rise and water properties may change due to the charges that pre-earthquake conditions create, but it is unclear how much notice those chemical clues could offer in terms of forecasting. It is also unknown whether the clues would appear at radically different times depending on the magnitude of the earthquake or the way in which it unfolds.

Still, Baragiola is optimistic about possible applications for the findings, even if predicting earthquakes days in advance remains impossible.

"If you have even half a minute, that's enough to tell school children to go under the bench. You can save a lot of lives," he said.

Researcher Dukes added that the sudden release of ozone from the ground could warn of other disasters, including landslides or ground shifts in excavation tunnels and mines.

"In mines or during landslides, any type of situation where you are breaking rock, you should see significant ozone output," she said.

Other predictors

The researchers' findings may also help to explain other phenomena associated with seismic events, like the appearance of so-called earthquake lights in the sky before a major quake. Those electrical fields could be a sign that sparks, caused by breaking rocks, lead to the ionization of molecules in the atmosphere.

Since publishing their results, Baragiola and Dukes have gotten calls from all over the world.

"I don't know the effect, but the discovery itself I think is very significant compared to other things. You could spend your life in academia without finding anything that you'd say ‘wow!', but this is a ‘wow!' thing," Baragiola said.

A likely next step for both research teams will collaboration with biologists or other animal experts to complete controlled studies on how animals react to the chemical changes they have observed.

Animal behavior may eventually be the key to getting earthquake warnings out.

Author: Sandy Hausman / gsw
Editor: Nathan Witkop