Brian,

The link can get you to a map of the world where you can get multibeam bathymetry. You can get the free software MBsystem elsewhere. This would take you approximately forever, and be overkill.

so, instead go to:
http://www.geomapapp.org/

and make yourself a nice grid of bathymetry at a lower resolution. Pay attention to where they have multibeam bathymetry vs. where they are using satellite bathymetry: the latter has a resolution of like 2 km, and is derived from the gravity field, maybe from sea-sat, which measures the elevation of the ocean surface.

I would be surprised if the area of the earthquake was not covered with multibeam bathymetry although HW is an expert and thinks it may not be. But, I don't know whether Japanese multibeam bathymetry would be public. Grids made from multibeam can have horizontal resolution of a couple meters in shallow water, and we are using a 20 m grid in Marmara Sea (100 m to 1300 m depth).

Also, Google Earth may have decent grids, although Oceanographers complain about these.

One comment though: you are going to spend a lot of time doing stuff that others are set up to do easily. You might be able to find something else to do related to earthquakes that might be understudied. If you want to, various of us could brainstorm with you on this page. For example, what is with the Puerto Rico trench swarms and do they occur in other subduction zones. Or 1000 other things.
Chris

• bathymetry