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Durham University

Department of Earth Sciences


Publication details for Prof Gillian Foulger

Einarsson, P., Bjornsson, S., Foulger, G.R., Stefansson, R. & Skaftadottir, T. (1981). Seismicity pattern in the South Iceland seismic zone, Earthquake prediction - An International Review. In Earthquake prediction (Maurice Ewing series 4). Simpson, D.W. & Richards, P.G. American Geophysical Union. 141-151.

Author(s) from Durham


The South Iceland Seismic Zone is an E-W trending zone of destructive, historic earthquakes, that takes up transform motion between the submarine Reykjanes Ridge and the Eastern Volcanic Zone in Southern Iceland. Major earthquake sequences affecting most of the 70 km long seismic zone recur at intervals ranging between 45 and 112 years. The sequences often begin with a large event (M≥7) in the eastern part of the zone followed by similar or slightly smaller events farther west. Single, damaging shocks occur more frequently, and are usually located at the ends of the zone. In spite of the clear E-W alignment of the epicenters, no surface evidence can be found for a major E-W striking fault. En echelon arrays of faults and fissures are found, however, indicating right-lateral strike-slip along northerly striking faults. Destruction zones of individual earthquakes also tend to be elongated in the N-S direction. The distribution of recent micro-earthquakes and the surface faulting during past large earthquakes seem to indicate that the seismicity is associated with brittle deformation of a 10–20 km wide zone located above an E-W trending zone of aseismic deformation in the lower crust or upper mantle.

No major earthquake sequence has occurred since 1896, and the whole zone has been very quiet for the last 50 years of instrumental observation. Judging from past history there is a high probability of a large earthquake occurring in the South Iceland Seismic Zone within the next few decades. A modest effort of earthquake prediction has been initiated, including radon monitoring of eight geothermal wells and the operation of volumetric strainmeters at seven sites.