The earthquake faults of North and South of Iceland generally move in opposite ways. It is easily explained. Here it is put into the context of convection rolls system.
The South Iceland Seismic Zone is easily detected, with mainly right lateral faults. In West Iceland, a much weaker seismic zone follows the same principle. In the North, the circumstances seem to be more complex, but the effect is the same, except that the rotation effect is oppositte and the faults become mainly left lateral.
The Borgarfjörður Zone in the West is strikingly similar to SISZ, but less active, as it is within the North Americal Plate already, and is only affected by local factors. In the North, the epicenter are found to be distributed along NW-aligned lines, forming blocks of a few polygons. The faults found there tend to be perpendicular to these blocks.
Geology of Iceland: https://en.wikipedia.org/wiki/Geology_of_Iceland