Here are some links that help explain the science behind this morning's magnitude 8.9 earthquake off the coast of Japan and resulting tsunami:
A summary from the USGS Earthquake Hazards Program
Mountain Beltway explains the geology of the quake
The USGS has a collection of links about earthquakes in Japan
Discovery News has video of the tsunami in Japan
And here's last month's post on the factors that contribute to the destructiveness of an earthquake
And Smithsonian's story about historic earthquakes and tsunamis in the Pacific Northwest
Please add your own links in the comments.