Jarðskjálftar á Íslandi árin 1956, 1957 og 1958

During this period, three seismograph stations were operated in Iceland, at Reykjavík, Akureyri and Vík. A new seismograph station was erected at Kirkjubæjarklaustur (Síða) in 1958, where one vertical Willmore seismograph is operated. The seismic activity in South Iceland was rather low during these years, but higher activity was observed in North Iceland. Earthquakes were felt in Iceland on 6 days during 1956, II days during ]957 and 9 days during 1958. The most pronounced felt earthquakes occurred as follows: 1956. June lst. in Southwest Iceland, maximum intensity VI, radius of perceptibility about 70 km. Ociober 29th in North Iceland, maximum intensity V, radius of perceptibility about 200 km. Epicenter off the coast. 1958. September 27th in North Iceland, maximum intensity VI, radius of perceptibility about 80 km. Desember 6th in North Iceland, maximum intensity IV, radius of perceptibility about 100 km. Epicenter off the coast. After the foundation of the seismograph stations at Akureyri, Vík, and Kirkjubæjarklaustur, the epicentre of Icelandic earthquakes can be determined with some accuracy. The epicentres seem to lie in severai smali regions, where some are known by frequent felt earthquakes, but other were unknown until recently. Two of these previously unknown epicentral regions have been very active in recent years, one in northwestern Vatnajökull (64.4°—64.8°N, 16.5°—18°W), and another around Torfajökull (63.7°-64.0°N, 19.0°-19.5°W). Some 25-30% of all Icelandic earthquakes during the period 1954 to 1958 have occurred in the first of these regions, and about 10% in the second region.