F. ROTH
Section "Earthquakes & Volcanism", GeoForschungsZentrum Potsdam, Germany
The South Iceland Seismic Zone is situated between two sections of the mid-atlantic ridge, i.e. the Reykjanes Ridge and the Eastern Volcanic Zone. It is no ideal transform fault, as it is not connecting both rifts at right angles and as the earthquakes do not occur on EW-trending left-lateral shear faults but on the conjugate, NS-oriented right-lateral, rupture planes. This is indicated by surface fault traces and aftershock distributions.
The stress field permanently generated by rifting with slightly more than 2 cm per year around this transform fault-like zone is computed and superimposed by the stress field changes induced by a series of 11 earthquakes (M >= 6) between 1706 and 1912. Finally, the post-seismic stress field of 1912 is extrapolated to the present, to see where highest stresses might have accumulated.
The stress is released by the series of events in the whole area, even though the ruptures planes are located on parallel NS-striking zones. The pre-seismic stress level for most events is high and pretty stable with the exception of situations when several strong shocks occur over a time span of several days, i.e. display typical main shock-aftershock patterns.