Chris, thanks for the info.

There is indeed higher res bathymetry of the Japan Trench as evidenced simply via looking at the area in Google Earth.

But, I have decided in the interest of expediency to just use some 1 arc-minute data that I have. It's from the ETOPO1 global data set. Although it's 'grainy', my rendering software should do a good job of interpolation. Besides, the focus is the quakes.

Your idea of rendering the Puerto Rico trench is a good one! I'll do that one right after the Japan Trench. Then later it might be interesting to go back to look at the Sumatra Trench.

It'll take me a few days to get rolling, though. I haven't done this in a while and need to re-remember a few things. Besides, I haven't quite decided which program I'm going to use. I have two at my disposal and each has their merits. What's easy in one is harder in the other. And as luck would have it what I want to do mixes the two.

Brian