A team of Russian and American scientists is attracting worldwide attention with a paper that finds that Japan's devastating March earthquake was preceded by marked atmospheric changes near the quake's epicenter immediately before it struck. The finding is the latest in more than a decade of research looking into the possibility that stresses in the Earth's crust before a major quake may be connected to pronounced changes in the atmosphere from the surface to its uppermost layers.
Spoiler alert: This does not mean scientists have found a way to predict earthquakes. Yet.
In a preliminary (non-peer-reviewed) paper released this week in Vienna, the team working in Southern California, Maryland, and several Russian institutions said that a rise in atmospheric temperatures was recorded over the epicenter of the Tohoku earthquake, just off the northeast coast of the island of Honshu, in the days immediately before the 9.0 shake occurred on March 11. The quake and subsequent tsunami killed 24,000 people in Japan and caused damage in much of the Pacific basin.
The researchers are led by Dimitar Ouzounov, an assistant professor of earth sciences at Southern California's Chapman University who also works at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Ouzounov has collaborated with others on several other papers that have documented anomalies in atmospheric conditions near quake epicenters. One paper documents rising atmospheric temperatures before two California quakes in September 2004: a 6.0 quake near Parkfield, on the San Andreas Fault northeast of Paso Robles, and a 5.5 tremor in Bodie, north of Mono Lake. Ouzounov told the Christian Science Monitor that he and his colleagues "have crunched data for more than 100 quakes in Asia and Taiwan ... and have found similar correlations for earthquakes with magnitudes bigger than 5.5 and depths less than 31 miles."
So what exactly did the team find when they looked at the atmospheric data from the Tohoku earthquake region? In layperson's shorthand, air temperatures above the monster quake's epicenter area rose and the upper atmosphere went nuts with loose subatomic particles and escaping heat. That is, something caused temperatures to rise in the lower atmosphere; in the ionosphere, much higher up, an unusually high level of electrons and outgoing long-wave radiation were detected.
What does that mean? Ouzounov et al. have seen this often enough to believe it could signal that seismic and tectonic processes--along faults that are about to rupture or at the boundaries of plates that are about to shift--have a direct linkage to these atmospheric changes. From Ouzounov's paper (citations omitted):
One of the possible explanations for this relationship is the Lithosphere-Atmosphere-Ionosphere Coupling mechanism, which provides the physical links between the different geochemical, atmospheric and ionospheric variations and tectonic activity. Briefly, the primary process is the ionization of the air produced by an increased emanation of radon (and other gases) from the Earth’s crust in the vicinity of [an] active fault. The increased radon emanation launches the chain of physical processes,which leads to changes in the conductivity of the air and a latent heat release (increasing air temperature) due to water molecules attachment (condensation) to ions."
Got that? If not, here's a translation from the arXiv blog at MIT's Technology Review:
The thinking is that in the days before an earthquake, the great stresses in a fault as it is about to give cause the releases large amounts of radon.
The radioactivity from this gas ionises the air on a large scale and this has a number of knock on effects. Since water molecules are attracted to ions in the air, ionisation triggers the large scale condensation of water.
But the process of condensation also releases heat and it is this that causes infrared emissions. "Our first results show that on March 8th a rapid increase of emitted infrared radiation was observed from the satellite data," say Ouzounov and co.
These emissions go on to effect the ionosphere and its total electron content.
Not everyone buys that explanation of the lithosphere-atmosphere-ionosphere mechanism. Here's an alternative theory as reported today in California Watch:
Friedmann Freund, another NASA scientist and a researcher at San Jose State University, says the observed atmospheric changes have nothing to do with radon and other gases escaping from the earth.
"There is no evidence that links radon emanation closely with seismic or pre-seismic events," he said. "There is another much more powerful, much more general and observationally supported process which causes massive air ionization, when stresses build up deep below earthquakes."
He says the electromagnetic changes are caused by extreme pressure on the rocks themselves. His theory is simple: If you squeeze a block of granite rock hard enough, it’ll become electrically active.
In 2007, Freund and others set up a laboratory experiment in which they squeezed a rock really hard, while detecting the emissions around it. As soon as pressure was applied to the rock, the electrical field around it changed.
To get back to that spoiler at the top: The new Tohoku findings will naturally prompt excitement over the idea that scientists have found an atmospheric signal of some impending major earthquakes and thus a way to forecast them. That idea has been thrown around in research papers since the late '90s at least. But the Christian Science Monitor quotes Ouzounov as saying that earthquake prediction based on his colleagues' findings is "far away."
Paper: "Atmosphere-Ionosphere Response to the M9 Tohoku Earthquake Revealed by Joined Satellite and Ground Observations," Ouzounov et al. (PDF)
Paper: Satellite IR Thermal Measurements Prior to the September 2004 Earthquakes in Central California, Ouzounov et al. (abstract)
Christian Science Monitor: Japan earthquake: Big, shallow quakes have a warning signal, say researchers
Technology Review, Physics arXiv Blog: Atmosphere Over Japan Heated Rapidly Before M9 Earthquake
California Watch: Scientists may have found quake warning signal
Paper: Stimulated infrared emission from rocks: assessing a stress indicator, Freund et al.