A time-dependent hazard assessment or long-term prediction was made 15 years ago for the area, suggesting that there was more than 80% probability that large earthquakes would occur in the SISZ during the next 25 years. It was predicted that the earthquakes would probably start at the eastern part of the seismic zone, with an event of magnitude 6.3 to 7.5, but during the next days or months a sequence of earthquakes would follow further west in the seismic zone (Einarsson 1985). Later revisions of magnitudes and hazard assessments assume that the largest possible earthquake in this zone could not exceed magnitude 7.2 (Ms) (Halldórsson 1987; Stefánsson and Halldórsson 1988). Based on these later estimates, the time-dependent hazard assessment just before the earthquakes was: 98% probability of a magnitude 6 earthquake during the next 25 years and lower probability for a larger one.