Paul Nicholls, the developer of the Christchurch Quake Map, has created an animated visualisation of all the Japanese earthquakes since March 11th.
The Google Map shows the magnitude and depth of each recorded quake. The size of the displayed polygons reflects the magnitude of each individual earthquake and its colour reflects the depth.
You can pause and resume the animation. A drop down menu also allows you to select to view the data for a specific day.