The destruction from the earthquake itself could've been a lot worse in Japan if the epicenter was closer to Japan and not 200km offshore. This map shows that the shaking in Japan was not of a destructive intensity in most areas. http://earthquake.usgs.gov/earthquakes/shakemap/global/shake...

PGA is generally better than magnitude for analyzing an earthquakes true intensity near cities http://en.wikipedia.org/wiki/Peak_ground_acceleration