Chris: Yesterday, we were pondering how to calculate the ‘speed’ for a plate when a plate’s speed can vary dramatically from one side to another. The answer is to calculate the ‘Root Mean Square’ (RMS) velocity by splitting the plate up into smaller fragments and calculating an area-weighted mean velocity. The fragmentation stage which can be tricky for irregular polygons such as tectonic plate; in the image above, I used a triangulation algorithm to split the Pacific plate up into – surprise! – a lot of tessellated triangles. It may be overkill, but it sure is pretty…