Japan is situated at the convergence point of four tectonic plates. Its location makes it a prime point for geological phenomenon such as earthquakes, volcanic activity. The four main islands of Japan are mostly mountainous terrain with the major cities located in the lower lying wetlands and coastal regions.
During a five day period between March 11 and 15, and after the 9.0 magnitude Tohoku Earthquake, a number of aftershocks were recorded by the US Geological Survey, Natural Hazards Support System. The Largest of the aftershocks was a magnitude 7.4 while most other ranged between 4.0 and 7.0.
The intensity of the Tohoku Earthquake as felt on land ranged from greater than 5.5 magnitude to greater than 7.0 magnitude along the eastern coast of Japan.
An earthquake of this proportion has many effects one being the shift of land mass. As recorded by NASA's Jet Propulsion Laboratory, Honshu, Japan's largest island, had land shifts ranging from 5.3m nearest the epicenter to 7.0cm in the southwest regions.
Another effect of the Tohoku Earthquake was the tsunami that followed. The Tohoku Tsunami reportedly made land fall in as little as 9 min after the occurrence of the earthquake. The map below shows the tsunami's movement over 15 hrs as it flows outward across the Pacific Ocean. The land along the east coast of japan, with in the inner most ring, was hit by the tsunami with in 30 min of the quake.