Wave heights are highly exaggerated in these screen shots from computer animations of the tsunami generated by the March 11, 2011, magnitude 9.0 earthquake. View northward in top image, southward in bottom image. Visit http://walrus.wr.usgs.gov/tsunami/sendai11/ to view the animations, created by USGS research geophysicist Eric Geist. A wave trough was the first part of the tsunami to reach the shore. Note the drawdown as water flows away from the shore while the first crest approaches.