If anyone want to check this, better way to do it: instead of having the arc concentric about the north end of the main rupture, they can have the same curvature. The center of curvature might be 100 km to the SE of the border (or, could just be the epicenter). The arcs would start at the border and continue to the NNW or NW.

I suppose if I am curious I could just take screen dumps of the map every day and save them. Not sure if I am organized enough...

Chris