The consistence between Hekla and its counterpart exactly 30° to the east is hard to explain. Hekla is on the 64th parallel, 19°40’W. 30° farther to the east on the 64th parallel, namely 10° 20’E, the landscape is oriented exactly the same way as Hekla. The volcano Hekla is a bit special, located in between the Eastern Rift Zone and the South Iceland Volcanic Belt. Therefore it is not pulled apart with the rift zone perpendicular to the convection rolls. The sideways drift of the tectonic plates therefore influences its alignment. It can be calculated as: A=(C+C/2)/2, where C stands for Convection orientation, and A is the allignment direction, in this case W35°N.
In Norway, there is no rift zone, but similar pressure vectors can occur, as the polygon pattern within the durctile part of the tectonic plates is exactly the same at these locations. That explains identical orientation of the topography.