According to a research published in the Geophysical Research Letters on September 15, 2011, the devastating earthquake that struck Japan in March 2011 may have caused disturbances in the highest layers of the atmosphere even before it impacted the ground. If proven correct, this discovery may one day allow early warning of giant earthquakes.
The 9.0 magnitude earthquake, one of the strongest ever recorded, caused a chain of micro-quakes all around the globe, as well as a catastrophic tsunami that destroyed the coastal regions of Japan. Scientists have discovered that the surface motion and the tsunamis triggered waves in the sky, reaching all the way up to the ionosphere: “Investigators measured these disruptions, called seismotraveling ionospheric disturbances, using about 1,000 global positioning system (GPS) receivers in Japan and Taiwan,” reads an article on ouramazingplanet.com, “Disruptions of the electrically charged particles in the ionosphere would lead to anomalies in radio signals between the ground receivers and the GPS satellites, data that scientists can measure.” “This signature in space that we can see with GPS could provide early warning that a tsunami is coming,” said Jann-Yenq “Tiger” Liu, an atmospheric scientist at Taiwan’s National Central University,
According to geodesist and geophysicist Kosuke Heki at Hokkaido University in Japan, author of the research, the Tohoku quake also may have generated ripples in the ionosphere before the quake struck. These electromagnetic anomalies, which affected GPS signals between satellites and the ground receivers. After having analized data coming more than 1,000 GPS receivers in Japan, Heiki discovered an 8% rise in the the total electron content of the ionosphere above the area hit by the earthquake about 40 minutes before the actual quake. This increase appeared greater near the epicenter. An analysis of historical GPS records revealed similar patterns during the magnitude 8.8 Chile earthquake in 2010.
This discovery may pave the way to the development of an earthquake early warning system, a system that could potentially save million of lives. In this regards, Heki cautioned that the ionosphere can be influenced by many other variables, like for instance solar storms: in order to develop and early-warning system for earthquakes based on this phenomenon, non-earthquake caused ionospheric anomalies would have to be ruled out first.
Heiki article can be found on Geophysical Research Letters.