The Reykjanes Ridge between 63°10′N and Iceland

Abstract: Along the Reykjanes Ridge from 63°10′N to 63°50′N we identify 10 en-echelon shallow closely spaced axial volcanic ridges (AVR). The AVRs are confined to the crest of the Reykjanes Ridge. This has been suggested to imply intense tectonic erosion of the ridges and subsequent sediment covering as they drift off axis. All AVRs studied are small and their length does not exceed that of individual eruptive fissures on land. Recent seismic activity is concentrated near Fuglasker seamount and the two AVRs in the Húllið graben. Tectonic strike changes drastically at the Skerjadjúp graben from N28°E to N40°E. Historic volcanic activity has been intense in this area with up to 14 eruptions, the last confirmed eruption occurring in 1926. New multibeam and backscatter data in the area of AVR 1 and the northernmost tip of AVR 2 show that the ridges were created by multiple eruptions, with clearly defined volcanic centres or cones, in contrast to monogenetic Pleistocene hyaloclastite ridges on land in Iceland with similar dimensions. In this area there was a series of eruptions during the years 1226–1238 in which the craters could have formed. The data also show normal faults in the Húllið graben. The western boundary faults have a drop of more than 25m, while the eastern faults are smaller but denser. [Copyright &y& Elsevier]