THE SIGNIFICANCE OF THE TWO EVENTS FOR EARTHQUAKE RESEARCH

Development of high level monitoring facilities as well as progress in understanding regional crustal processes were of significance in coping with the year 2000 earthquakes, both in providing useful hazard assessments and warnings as well as in collecting data for future research. A significant milestone was the SIL-project (1988-1995), building the high-level seismic SIL-system. It was a concerted effort of the Nordic countries toward earthquake prediction research in the SISZ (Stefánsson et al. 1993). The PRENLAB and PRENLAB-2 projects of the European Union 1996-2000 (Stefánsson et al. 1999) were also significant in this development. PRENLAB stands for Earthquake-Prediction Research in a Natural Laboratory. The SIL-project as well as the PRENLAB projects were based on a physical approach to earthquake prediction research, in collection of data and in their multidisciplinary approach to earthquake prediction research. At the same time emphasis has been on automatic or fast evaluation of observations with the goal of ultimately providing short-term warnings. Increased earth activity, seismic and volcanic, has also spurred the recent efforts to build up a continuously recording GPS network in addition to the GPS campaigns carried out repeatedly during the last decade. InSAR technology has been applied with good results to monitor volcanic areas as well as seismic and interseismic deformations in the fault zones. Volumetric strain measurements have been ongoing since 1980 in and near the SISZ especially to monitor short-term strain changes, with especially good results related to volcanic eruptions (Linde et al. 1994) Measurements of water level (pressure) in boreholes in hydrothermal fields with deep roots have been initiated during the last few years as a part of monitoring strain changes in the crust. Continuous monitoring of water level in some boreholes in the SISZ was in preparation before the earthquakes and has gradually come in operation after the earthquakes. A network of strong motion instruments was installed in Iceland during the last decade, especially in the SISZ. The multidisciplinary earthquake data that have been collected for the two recent earthquakes in the SISZ - the seismic and intensity data, deformation data and hydrological data are of enormous significance for ongoing research aiming at understanding and for modelling earthquake release processes in the SISZ. The study and modelling based on historical seismicity as well as on mapping of earthquake faults will be revised in the light of the new data. The data collected and the ongoing research have a focus on mitigating seismic risk in general, and on more complete and more secure warnings for earthquakes, both in this zone and worldwide.