Quote Originally Posted by cantab View Post
(A sidenote about your plate centroids - if you create latitudes and longitudes at random, you don't get a uniform distribution over the planet, since 1°x1° is a much smaller area near the poles that at the equator. This probably doesn't really matter, but bear it in mind.)
I'm working in spherical coordinates - 1 degree at the pole is exactly the same as 1 degree at the equator. That's why the poles *tend* to be one single plate each, the distance covered is rather small compared to at the equator. I have had versions that had 2 plates meet at or near a pole though.

It might be interesting to see if our two methods are combinable. You seem to have a more accurate math model for the plate boundaries, and I have the coordinate math.