It was an abduction type of quake, which means that one tectonic plate (the Pacific) slid over top of another (the North American). The effect of one part of the earth's crust sliding over the other is the consequent quake, then tsunami and also other subtle effects such as land elevation changes (new valleys or hills may appear). Also, at this magnitude of force, the earth's rotation is increased a little more, that's why all the GPS satellites had to be recalibrated since we're now 2+ micro seconds slower.
A tsunami hit japan after the earthquake.
In Japan
The 8.9 Japan Earthquake
earthquake in ocean
Friday
East of Sendai
In march 2011
The epicenter of the earthquake was offshore, close to Sendai, Japan.
The plates moved so this can occur the earthquake.
Tectonic plates shifted, creating the earthquake.
Before you were born
The Northeastern Coast.