The pattern of extensive strain accumulation on a tectonic plate before March 11 largely matched the actual fault slip that caused the Great East Japan Earthquake, a team of researchers said.
The pattern of extensive strain accumulation on a tectonic plate before March 11 largely matched the actual fault slip that caused the Great East Japan Earthquake, a team of researchers said.
The finding could help forecast the spatial extent of a coming earthquake based on strain accumulation data.
The team, led by Kazuki Koketsu, professor at the Earthquake Research Institute of the University of Tokyo, used seismograms and Global Positioning System measurement network data to analyze the extent of the fault slip during the March 11 earthquake.
They also analyzed data from a quiescent period before the earthquake and evaluated the strain accumulation, including distortions, due to the continental plate being dragged down by the oceanic plate, with which it was bonded.
They found that the distributions of the two quantities were largely similar.
Based on records of known earthquakes before the March 11 disaster, it was believed that earthquakes of magnitude 7 to 8 occurred separately along different sections of the Japan Trench.
However, six earthquakes coincided and created the magnitude-9.0 mega-quake on March 11.
According to an analysis by the Geospatial Information Authority of Japan, strain accumulation is also distributed more extensively than any single hypothetical seismic source along the Nankai Trough, an underwater plate interface off the southern coast of Japan.
There are instances in the past when an earthquake simultaneously ruptured the Tokai, Tonankai and Nankai seismic sources along the Nankai Trough.
Following the Great East Japan Earthquake, attention is focused on the possibility of another mega-quake bigger than any single event envisaged so far.
Extensive strain accumulation has also been found along the Kuril Trench to the east of Hokkaido.