Monday, 30 May 2011

Do atmospheric changes before Japan’s big quake indicate predictability?


Image Credit: NASA
Image Credit: NASA

Is it time to throw our hats in the air and shout hurrah? Do atmospheric data related to the Japan earthquake indicate a leap forward in our ability to predict earthquakes?

In the days before March 11, 2011 – when the 9.0-magnitude Tohoku earthquake struck off the coast of Japan – data collected by scientists indicated that Earth’s atmosphere above the earthquake’s epicenter was heating up. The data came from satellite observations showing large increases in electron density and infrared radiation (or heat) emissions above the earthquake’s epicenter on March 8, 2011.

Scientists presented these preliminary results at the annual European Geosciences Union meeting in Vienna, Austria on April 8, 2011. A story in MIT’s Physics arXiv blog on May 18, 2011 quickly went as viral as one might expect, with 5,000+ Facebook likes and 800+ tweets. It’s exciting because a rise in temperature above an earthquake epicenter in the days before a major eruption has implications for our future ability to predict earthquakes. Is it time to throw our hats in the air and shout hurrah? Do the atmopsheric data related to the March 11 earthquake indicate a leap forward in our ability to predict earthquakes?

Image Credit: NASA

The science of earthquake predictions is still in its infancy. Many scientists doubt that reliable and accurate earthquake predictions are even possible. Presently, scientists are fairly good at predicting where on Earth earthquakes are likely to occur – along the shifting boundaries of moving land plates. But scientists have been unable to determine exactly when an earthquake is going to strike. Hence, efforts to mitigate the destructive impacts of earthquakes are aptly focused on reinforcing vulnerable buildings in earthquake prone areas and ensuring that people in high-risk areas are adequately prepared for a natural disaster.

Still, the lure of earthquake prediction remains appealing despite its elusiveness simply because it could save so many lives. Siesmologist Mike Blanpied of the United States Geological Survey summarized this sentiment in a March 11, 2011 interview with EarthSkywhen he stated:

There [are] increased amounts of data, new theories and powerful computer programs and scientists are using those to explore ways that earthquakes might be predicted in the future. We can certainly hope that someday we’ll be in a world where an earthquake can be anticipated and predicted before it occurs.

The earthquake in Japan on March 11, 2011 is likely to be the best studied earthquake in modern history. Scientists from the U.S. and Russia have been busy analyzing the atmospheric conditions above the epicenter of the Tohoku earthquake to evaluate whether there were any precursory events that could have indicated that an earthquake was about to occur. That is how they found the increases in electron density and infrared radiation (or heat) emissions above the earthquake’s epicenter.

The scientists used satellite data to collect information on outgoing long-wave radiation and the electron content of the ionosphere. The ionosphere is the layer of the Earth’s atmosphere that contains a high concentration of charged ions and free electrons, which are able to reflect radio waves. The ionosphere extends from about 80 to 1000 kilometers (50 to 620 miles) above the surface of the Earth.

Layers of the atmosphere. Image credit: Wikipedia.

The scientists discovered that there was a rapid increase of emitted infrared radiation (or heat) on March 8, 2011 near the epicenter, and that radiation levels peaked just prior to the earthquake. The scientists also observed that the total electron content of the ionosphere near the epicenter increased from March 3 to March 10, then returned to background levels after the main earthquake subsided.

According to the scientists, similar atmospheric anomalies have been observed a few days prior to the recent earthquakes in China (magnitude 7.9, 2008), Italy (magnitude 6.3, 2009), Samoa (magnitude 7, 2009), Haiti (magnitude 7.0, 2010) and Chile (magnitude 8.8, 2010).

The scientists attribute these precursory atmospheric events to the phenomena of Lithosphere-Atmosphere-Ionosphere (LAI) Coupling. During LAI Coupling the air is ionized by the emission of radon and other gases from the Earth’s crust in the vicinity of an active fault. The ionization of air initiates a cascade of other atmospheric reactions including the condensation of water molecules and the release of latent heat, which increases air temperatures.

The preliminary scientific findings about the Great Tohoku earthquake were summarized by Dimitar Ouzounov from NASA’s Goddard Space Flight Center in a paper presented at the annual European Geosciences Union meeting in Vienna, Austria on April 8, 2011.

While atmospheric anomalies appear to precede and coincide with earthquakes, it is still unclear how accurate and reliable such measures are for predicting earthquakes. Future research to improve our understanding of atmospheric changes that precede earthquakes will likely follow given the important and compelling nature of the scientific findings.