The video below gives an outstanding view of the buildup in terms of groundshaking to the Japanese earthquake of 2011 and the aftershocks that followed. It is worth watching through with sound as well. As the year goes on, the regularity of earthquakes in the area is made clear, as is the location of the boundaries with relation to Japan. However as March the 10th/11th commences, there is a huge release of energy that takes some months to subside.
This is an excellent visual representation of the scale and sudden onset of the event.