Dynjandi, a mighty waterfall, is located in the Western Fjords area of Iceland, far away from the volcanic zones. Still the orientation of the waterfall can be calculated in the same way as the volcanic zones:
It is located on 65.7°N, about the same latitude as Dettifoss. So those two waterfalls are aligned the same way!
Just have a look:
So is there a basic reason for this?