The epicenter of the Great East Japan Earthquake was located in an area where oceanic and continental plates are tightly bonded, according to the Geospatial Information Authority of Japan.
A report of this discovery is due to be published online by the British science journal Nature on June 16.
Measurements of the strength of an inter-plate bonding could help predict the epicenters of possible major earthquakes in the future.
The agency's analysis using the global positioning system indicated that an oceanic plate and a continental plate were firmly bonded and unable to shift around the epicenter of the quake before it hit northeast Japan on March 11.
An excessively strong bond between plates would allow the rapid accumulation of stress between the plates--stress that cannot be fully released even by a series of magnitude-7 earthquakes.
The bond would also push down the continental plate further when the oceanic plate shifts, causing the land to sink 1 centimeter a year.
It has been believed that a coastal terrace could be created if a major earthquake hit a coastal area and exerted upward pressure on sunken land.
According to the results of the latest analysis, however, sunken lands in quake-hit coastal areas were only partially raised after the quake. Researchers are closely watching the coastal areas to see if sunken lands will gradually rise.
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