Volcanic activity has stamped its mark on the history of the Icelanders. The damaging factors of volcanic eruptions and the range of their effects are shown in Table 1. The four factors causing the most serious damage in Iceland are tephra, lava, gases, and jokulhlaups. The most damaging tephra falls were from Hekla in 1104 and from Myrdalsjökull, a hitherto unknown eruption, in about 1375. In lowland areas, a tephra fall leads to long abandonment of farms, when the thickness of the tephra layer, as freshly fallen, exceeds 25 cm. Two lava flows were exceptionally destructive, the Lakagigar lava flow in 1783 and that on Heimaey in 1973. Most destructive among the numerous jokulhlaups were probably those from Öraefajökull in 1362 and from Katla shortly before 1179. The worst disaster in Iceland's history was caused by the gases—mainly fluorine and sulphuric compounds—emitted during the Lakagigar eruption in 1783. This disaster excluded, volcanic eruptions have directly caused fewer losses of life than snow avalanches have done. And bearing in mind the utilization of the natural heat, it seems safe to claim that in spite of severe blows from eruptions and earthquakes, the volcanic character of Iceland makes it now a better country to live in than it would otherwise be. (Translated by U.S. Department of State; further translation and editing by Richard S.Williams, Jr., U.S. Geological Survey, Reston, Virginia 22092).