Jarðskjálftar á Íslandi

Abstract

Larger earthquakes in Iceland occur mainly in two zones, a narrow E-W trending zone in S-Iceland and 75 km broad zone off the northern coast. Destruction and ground displacement due to the earthquake sequences of J784 (Ms 7.5-8), 1896 Mg 7-7.5) and 1912 (Ms 7) are described. Considerable seismic activity is observed within the active volcanic zones. The earthquakes occur mainly as swarms of magnitude less than Ms 5. Volcanic eruptions are generally preceded by swarms of earthquakes. Examples of such premonitory earthquakes are given for the eruption of Heimaey 1973, Katla 1625, Lakagígar 1783, Mývatn Fires 1724-1729, Askja and Sveinagjá 1875.