The purpose of this paper is to describe and to model long- and short-term processes that preceded two large earthquakes that occurred in 2000 in the South Iceland seismic zone (SISZ). The results are based on some key findings from multinational earthquake-prediction research projects in the SISZ since 1988. It involves a fusion of significant old and new results. The paper presents a new hypothesis for earthquake build-up processes in the region, followed by a discussion on how interseismic and preseismic observations can be explained by this model and a discussion about a plausible earthquake cycle in light of the new hypothesis.
The research described here started in 1988 with the South Iceland Lowland (SIL) project. A significant outcome was the development of a seismic acquisition and evaluation system, the SIL system, retrieving source information from earthquakes down to magnitude zero. The research continued with the use of more multidisciplinary and multinational projects, revealing new information about crustal processes related to large earthquakes in the area. The validity of the work was tested in 2000 when two magnitude 6.6 (MS) earthquakes occurred in the central part of the SISZ. The earthquakes had a long-term assessment of place. A short-term warning (“within short”) about the location and size of a probable impending earthquake was issued 25 hours before the second earthquake.