When the Japan Meteorological Agency issues a tsunami warning, do not disregard it thinking you've got a better handle on the factors in play. The Japanese have their country monitored thoroughly and take disaster preparedness more seriously than anything I've seen in the US.
http://www.jma.go.jp/jma/indexe.html (currently has warning)
With historical tsunami information:
http://www.jma.go.jp/en/tsunami/list.html