Earthquake fractures in the districts Land and Rangarvellir in the south Iceland seismic zone

Large earthquakes have been accompanied by extensive surface fracturing throughout the South Iceland Seismic Zone, one of the major fracture zones of the Mid-Atlantic plate boundary. Fracture systems in the easternmost part of the zone, in the districts Land and Rangarvellir, have been mapped. The fractures generally strike NE and form en echelon arrays which trend N-S. They are interpreted as the surface expression of underlying right-lateral strike-slip faults. The faults are arranged side by side within the E-W trending seismic zone. The reason for this unusual configuration is poorly understood, but the tentative explanation is given, that the seismic zone is a fracture front migrating S in response to a southwards propagation of the eastern rift zone of Iceland. -Authors