Study: Ozone From Rock Fracture Could Serve As Earthquake Early Warning
— Researchers the world over are seeking reliable ways to predict earthquakes, focusing on identifying seismic precursors that, if detected early enough, could serve as early warnings.
New research, published this week in the journal Applied Physics Letters, suggests that ozone gas emitted from fracturing rocks could serve as an indicator of impending earthquakes. Ozone is a natural gas, a byproduct of electrical discharges into the air from several sources, such as from lightning, or, according to the new research, from rocks breaking under pressure.
Scientists in the lab of Raúl A. Baragiola, a professor of engineering physics in the University of Virginia School of Engineering and Applied Science, set up experiments to measure ozone produced by crushing or drilling into different igneous and metamorphic rocks, including granite, basalt, gneiss, rhyolite and quartz. Different rocks produced different amounts of ozone, with rhyolite producing the strongest ozone emission.
Some time prior to an earthquake, pressures begin to build in underground faults. These pressures fracture rocks, and presumably, would produce detectable ozone.
To distinguish whether the ozone was coming from the rocks or from reactions in the atmosphere, the researchers conducted experiments in pure oxygen, nitrogen, helium and carbon dioxide. They found that ozone was produced by fracturing rocks only in conditions containing oxygen atoms, such as air, carbon dioxide and pure oxygen molecules, indicating that it came from reactions in the gas. This suggests that rock fractures may be detectable by measuring ozone.
Baragiola began the study by wondering if animals, which seem – at least anecdotally – to be capable of anticipating earthquakes, may be sensitive to changing levels of ozone, and therefore able to react in advance to an earthquake. It occurred to him that if fracturing rocks create ozone, then ozone detectors might be used as warning devices in the same way that animal behavioral changes might be indicators of seismic activity.
He said the research has several implications.
“If future research shows a positive correlation between ground-level ozone near geological faults and earthquakes, an array of interconnected ozone detectors could monitor anomalous patterns when rock fracture induces the release of ozone from underground and surface cracks,” he said.
“Such an array, located away from areas with high levels of ground ozone, could be useful for giving early warning to earthquakes.”
He added that detection of an increase of ground ozone might also be useful in anticipating disasters in tunnel excavation, landslides and underground mines.
Baragiola’s co-authors are U.Va. research scientist Catherine Dukes and visiting student Dawn Hedges.
— By Fariss Samarrai
Ozone generation by rock fracture: Earthquake early warning?
Engineering Physics, University of Virginia, Charlottesville, Virginia 22904, USA
(Received 10 August 2011; accepted 26 October 2011; published online 14 November 2011)
We report the production of up to 10 ppm ozone during crushing and grinding of typical terrestrial crust rocks in air, O2 and CO2 at atmospheric pressure, but not in helium or nitrogen. Ozone is formed by exoelectrons emitted by high electric fields, resulting from charge separation during fracture. The results suggest that ground level ozone produced by rock fracture, besides its potential health hazard, can be used for early warning in earthquakes and other catastrophes, such as landslides or land shifts in excavation tunnels and underground mines.
This isn’t a new idea though, a similar study was published in the Journal Remote Sensing (well before the editor resigned)
Variation in atmospheric ozone concentration following strong earthquakes
The changes in atmospheric ozone concentration for earthquakes (with a magnitude greater than 5.0 on the Richter scale and a depth of focus less than 35 km), which have occurred worldwide during the period from September to March for the years 1991–2006, have been studied with the help of satellite data obtained from Nimbus‐7 Total Ozone Mapping Spectrometer (TOMS), Earth probe TOMS and the Ozone Monitoring Instrument. The trend of variation in total ozone concentration after all these earthquakes was found to be similar. The ozone concentration was low on the day of the earthquake, increased gradually after the earthquake and reached a maximum value and thereafter decreased to its normal value. The increase in ozone concentration was found to be dependent on the magnitude of the quake, depth of focus, wind direction and geographical location of the epicentre.