Bulletin of Volcanology

, 71:715 | Cite as

Controls on the geometry of a Holocene crater row: a field study from southwest Iceland

  • Maria H. Jenness
  • Amy E. Clifton
Research Article


The Reykjanes Peninsula rift zone in southwest Iceland is a highly oblique segment of the Mid-Atlantic ridge system which accommodates NW–SE extension during rifting episodes that consist of eruptions and normal faulting, and E–W left-lateral shear strain along strike-slip faults during longer amagmatic periods. Dominant tectonic features on the peninsula are a series of generally NE-striking, sub-parallel eruptive fissures and normal faults, and a cross-cutting zone of N–S striking, right-lateral strike-slip faults. The last series of rifting episodes ended in 1227, and a proposed 1,000 year cyclicity predicts the start of a new series of eruptions within the next 200 years. In order to more accurately characterize the nature of eruptions on the Reykjanes Peninsula, we present a new, spatially accurate map of the ∼2,350 year old Sundhnúkur crater row in the western part of the peninsula, which was examined in detail in order to determine the structural controls on crater row geometry and to understand the interactions that take place between eruptive fissures and pre-existing geological structures. Volcanism is sometimes influenced by small perturbations in the surroundings such as gravitational loading, topography, changes in crustal properties or the presence of fault zones, but there are few field examples showing how fissures are influenced by these pre-existing structures. We identify 27 fissure segments, ranging in strike from 006° to 053°, with varying spacing and overlap between them. Significant local variability in strike and stepping sense of segments occurs in proximity to topographic highs as well as within zones of faulting that pre-date the crater row. Strike also varies at the northern end of the crater row as it approaches a region of older crust at the rift margin. Our data support numerical and laboratory modeling results which show that local topography, pre-existing fractures and crustal properties influence the path taken by magma on its way through the shallow crust.


Crater row Reykjanes Peninsula Fissure segmentation Oblique rifting 



The authors would like to thank Kirby Young for his insight and assistance both during field work and during the writing of this manuscript. We also thank Magnus Ellström for assistance with field work. Freysteinn Sigmundsson assisted in the final stages of manuscript preparation. We thank Thorvaldur Thordarson and an anonymous reviewer for constructive comments which improved the quality of the paper. This work was supported by a student research grant from Bates College (M. Jenness) and grants from the Icelandic Research Fund and the Reykjavík Energy Company (A. Clifton).

Supplementary material

445_2009_267_Fig1_ESM.gif (544 kb)

(GIF 544 kb)

445_2009_267_Fig1_ESM.eps (17.3 mb)
High resolution image file (EPS 17.2 mb)


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Medomak Valley Land TrustWaldoboroUSA
  2. 2.Nordic Volcanological Center, Institute of Earth SciencesUniversity of IcelandReykjavikIceland

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