March 11, 2011 an earthquake of magnitude 9 occurred off the east coast of Honshu, 160 km east of the city of Sendai and 400 km north-east of Tokyo. Although Japan is a highly seismic region, the event has surprised the experts by its size and location. This is an earthquake the most violent of the globe, of the same magnitude as that which occurred in Sumatra in December 2004 resulting in the death of 280,000 people. In Japan, the official death toll is nearly 16,000 dead and over 3,000 missing-but it could be underestimated.
The region was not particularly under surveillance since the fault was expected that the impending rupture was located along the Nankai Trough, several hundred miles away, off to Osaka. The historical seismicity of the region did not indicate any event of this magnitude. (Read Great earthquakes always surprising )