One aspect of science and proof is repeated occurrence. This is found in Central Iceland where four axis of volcanic activity appear parallel to each other, each occupying one of identical polygons of the convection rolls system under the country:
By simply adding a red line on the lines of the original ISOR map, it can be seen how each volcanic zone occupies one polygon. One of them is the main rift zone, the ER-line. These polygons are all east of the Reykjanes Ridge. The Snæfellsnes Belt is found at a similar latitude, and is due to forces acting to a different direction, that is NW and therefore takes on a different orientation.