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The Krafla fissure swarm, Iceland, and its formation by rifting events

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Abstract

Fissure swarms at divergent plate boundaries are activated in rifting events, during which intense fracturing occurs in the fissure swarm accompanied by intrusion of magma to form dikes that sometimes lead to eruptions. To study the evolution of fissure swarms and the behaviour of rifting events, detailed mapping was carried out on fractures and eruptive fissures within the Krafla fissure swarm (KFS). Fracture densities of dated lava flows ranging from 10,000 years bp to ~30 years old were studied, and the fracture pattern was compared with data on the historical Mývatn rifting episode (1724–1729) and the instrumentally recorded Krafla rifting episode (1975–1984). Additionally, the interaction of transform faults and fissure swarms was studied by analysing the influence of the Húsavík transform faults on the KFS. During the historical rifting episodes, eruptions on the fissure swarm occurred within ~7 km from the Krafla central volcano, although faults and fractures were formed or activated at up to 60–70 km distance. This is consistent with earlier rifting patterns, as Holocene eruptive fissures within the KFS are most common closer to the central volcano. Most fractures within the central Krafla caldera are parallel to the overall orientation of the fissure swarm. This suggests that the regional stress field is governing in the Krafla central volcano, while the local stress field of the volcano is generally weak. A sudden widening of the graben in the northern KFS and a local maximum of fracture density at the junction of the KFS and the extrapolation of the Húsavík transform fault zone indicates possible buried continuation of the Húsavík transform fault zone which extends to the KFS. Eruptive fissures are found farther away from the Krafla central volcano in the southern KFS than in the northern KFS. This is either due to an additional magma source in the southern KFS (the Heiðarsporður volcanic system) or caused by the Húsavík transform faults, transferring some of the plate extension in the northern part. Fracture density within particular lava flow fields increases with field age, indicating that repeated rifting events have occurred in the fissure swarm during the last 10,000 years bp. The fracture density in the KFS is also generally higher closer to the Krafla central volcano than at the ends of the fissure swarm. This suggests that rifting events are more common in the parts of the fissure swarm closer to the Krafla central volcano.

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References

  • Abdallah A, Courtillot V, Kasser M, Ledain AY, Lepine JC, Robineau B, Ruegg JC, Tapponnier P, Tarantola A (1979) Relevance of Afar seismicity and volcanism to the mechanics of accreting plate boundaries. Nature 282:17–23. doi:10.1038/282017a0

    Article  Google Scholar 

  • Baer G, Hamiel Y (2010) Form and growth of an embryonic continental rift: InSAR observations and modelling of the 2009 western Arabia rifting episode. Geophys J Int 182:155–167. doi:10.1111/j.1365-246X.2010.04627.x

    Google Scholar 

  • Bergerat F, Angelier J (2008) Immature and mature transform zones near a hot spot: the South Iceland Seismic Zone and the Tjornes Fracture Zone (Iceland). Tectonophysics 447:142–154. doi:10.1016/j.tecto.2006-05.046

    Article  Google Scholar 

  • Björnsson A, Sæmundsson K, Einarsson P, Tryggvason E, Grönvold K (1977) Current rifting episode in North Iceland. Nature 266:318–323. doi:10.1038/266318a0

    Article  Google Scholar 

  • Buck WR, Einarsson P, Brandsdóttir B (2006) Tectonic stress and magma chamber size as controls on dike propagation: constraints from the 1975–1984 Krafla rifting episode. J Geophys Res Solid Earth 111:B12404. doi:10.1029/2005JB003879

    Article  Google Scholar 

  • Böðvarsson G, Walker GPL (1964) Crustal drift in Iceland. Geophys J Roy Astron Soc 8:285–300. doi:10.1111/j.1365-246X.1964.tb06295.x

    Google Scholar 

  • Calais E, d'Oreye N, Albaric J, Deschamps A, Delvaux D, Deverchere J, Ebinger C, Ferdinand RW, Kervyn F, Macheyeki AS, Oyen A, Perrot J, Saria E, Smets B, Stamps DS, Wauthier C (2008) Strain accommodation by slow slip and dyking in a youthful continental rift, East Africa. Nature 456:783–787. doi:10.1038/nature07478

    Article  Google Scholar 

  • DeMets C, Gordon RG, Argus DF, Stein S (1994) Effect of recent revisions to the geomagnetic reversal time-scale on estimates of current plate motions. Geophys Res Lett 21:2191–2194. doi:10.1029/94GL02118

    Article  Google Scholar 

  • Dziak RP, Bohnenstiehl DR, Cowen JP, Baker ET, Rubin KH, Haxel JH, Fowler MJ (2007) Rapid dike emplacement leads to eruptions and hydrothermal plume release during seafloor spreading events. Geology 35:579–582. doi:10.1130/g23476a.1

    Article  Google Scholar 

  • Dziak RP, Smith DK, Bohnenstiehl DR, Fox CG, Desbruyeres D, Matsumoto H, Tolstoy M, Fornari DJ (2004) Evidence of a recent magma dike intrusion at the slow spreading Lucky Strike segment, Mid-Atlantic Ridge. J Geophys Res Solid Earth 109:B12102. doi:10.1029/2004jb003141

    Article  Google Scholar 

  • Ebinger C, Ayele A, Keir D, Rowland J, Yirgu G, Wright T, Belachew M, Hamling I (2010) Length and timescales of rift faulting and magma intrusion: the afar rifting cycle from 2005 to present. Ann Rev Earth Planet Sci 38:439–466. doi:10.1146/annurev-earth-040809-152333

    Article  Google Scholar 

  • Einarsson P (1978) S-wave shadows in the Krafla Caldera in NE-Iceland, evidence for a magma chamber in the crust. Bull Volcanol 41:187–195. doi:10.1007/BF02597222

    Article  Google Scholar 

  • Einarsson P (1987) Compilation of earthquake fault plane solutions in the North Atlantic and Arctic Oceans. In: Kasahara K (ed) Recent plate movements and deformation. American Geophysical Union, Washington, pp 47–62

    Chapter  Google Scholar 

  • Einarsson P (1991a) Earthquakes and present-day tectonism in Iceland. Tectonophysics 189:261–279. doi:10.1016/0040-1951(91)90501-I

    Article  Google Scholar 

  • Einarsson P (1991b) Umbrotin við Kröflu 1975–1989. In: Garðarsson A, Einarsson Á (eds) Náttúra Mývatns. Hið íslenska náttúrufræðifélag, Reykjavík

    Google Scholar 

  • Einarsson P (2008) Plate boundaries, rifts and transforms in Iceland. Jökull 58:35–58

    Google Scholar 

  • Einarsson P, Sæmundsson K (1987) Earthquake epicenters 1982–1985 and volcanic systems in Iceland (map). In: Sigfússon ÞI (ed) Í hlutarins eðli, Festschrift for Þorbjörn Sigurgeirsson. Menningarsjóður, Reykjavík

    Google Scholar 

  • Elíasson S (1979) Kerlingarhólar í Gjástykki (in Icelandic). Náttúrufræðingurinn 49:51–63

    Google Scholar 

  • Eriksson PI, Riishuus MS, Sigmundsson F, Elming S-Å (2011) Magma flow directions inferred from field evidence and magnetic fabric studies of the Streitishvarf composite dike in east Iceland. J Volcanol Geotherm Res 206:30–45. doi:10.1016/j.jvolgeores.2011.05.009

    Article  Google Scholar 

  • Fox CG, Radford WE, Dziak RP, Lau TK, Matsumoto H, Schreiner AE (1995) Acoustic detection of a sea-floor spreading episode on the Juan-de-Fuca Ridge using military hydrophone arrays. Geophys Res Lett 22:131–134. doi:10.1029/94GL02059

    Article  Google Scholar 

  • Garcia S, Dhont D (2005) Structural analysis of the Husavik–Flatey transform fault and its relationships with the rift system in Northern Iceland. Geodin Acta 18:31–41. doi:10.3166/ga.18.31-41

    Article  Google Scholar 

  • Grönvold K, Halldórsson SA, Sigurðsson G, Sverrisdóttir G, Óskarsson N (2008) Isotopic systematics of magma movement in the Krafla Central Volcano, North Iceland. In: Goldschmidt conference. Vancouver, Canada, p A331

  • Guðmundsson A (1995) Infrastructure and mechanics of volcanic systems in Iceland. J Volcanol Geotherm Res 64:1–22. doi:10.1016/0377-0273(95)92782-Q

    Article  Google Scholar 

  • Guðmundsson A (2007) Infrastructure and evolution of ocean-ridge discontinuities in Iceland. J Geodyn 43:6–29. doi:10.1016/j.jog.2006.09.002

    Article  Google Scholar 

  • Guðmundsson A, Brynjólfsson S, Jónsson MT (1993) Structural-analysis of a transform-fault rift-zone junction in North Iceland. Tectonophysics 220:205–221. doi:10.1016/0040-1951(93)90232-9

    Article  Google Scholar 

  • Hamling IJ, Ayele A, Bennati L, Calais E, Ebinger CJ, Keir D, Lewi E, Wright TJ, Yirgu G (2009) Geodetic observations of the ongoing Dabbahu rifting episode: new dyke intrusions in 2006 and 2007. Geophys J Int 178:989–1003. doi:10.1111/j.1365-246X.2009.04163.x

    Article  Google Scholar 

  • Helgason J, Zentilli M (1985) Field characteristics of laterally emplaced dikes: anatomy of an exhumed Miocene dike swarm in Reydarfjördur, eastern Iceland. Tectonophysics 115:247–274. doi:10.1016/0040-1951(85)90141-6

    Article  Google Scholar 

  • Hjartardóttir ÁR, Einarsson P, Sigurðsson H (2009) The fissure swarm of the Askja volcanic system along the divergent plate boundary of N Iceland. Bull Volcanol 71:961–975. doi:10.1007/s00445-009-0282-x

    Article  Google Scholar 

  • Hooper A, Ófeigsson B, Sigmundsson F, Lund B, Einarsson P, Geirsson H, Sturkell E (2011) Increased capture of magma in the crust promoted by ice-cap retreat in Iceland. Nat Geosci 4:783–786. doi:10.1038/NGEO1269

    Article  Google Scholar 

  • Höskuldsson A, Dyhr C, Dolvik T (2010) Grænavatnsbruni og Laxárhraun yngra (in Icelandic). In: Autumn conference of the Iceland Geoscience Society. Reykjavík, pp 41–42

  • Jakobsdóttir SS, Roberts MJ, Guðmundsson GB, Geirsson H, Slunga R (2008) Earthquake swarms at Upptyppingar, North-East Iceland: a sign of magma intrusion? Stud Geophys Geod 52:513–528

    Article  Google Scholar 

  • Jóhannesson H, Sæmundsson K (1998) Geological map of Iceland. Bedrock geology. Icelandic Institute of Natural History, Reykjavík

    Google Scholar 

  • Jónasson K (1994) Rhyolite volcanism in the Krafla central volcano, north-east Iceland. Bull Volcanol 56:516–528. doi:10.1007/BF00302832

    Article  Google Scholar 

  • Jónasson K (2005) Magmatic evolution of the Heiðarsporður ridge, NE-Iceland. J Volcanol Geotherm Res 147:109–124. doi:10.1016/j.jvolgeores.2005.03.009

    Article  Google Scholar 

  • Magnúsdóttir S, Brandsdóttir B (2011) Tectonics of the Þeistareykir fissure swarm. Jökull 61:65–79

    Google Scholar 

  • Mattsson HB, Höskuldsson Á (2011) Contemporaneous phreatomagmatic and effusive activity along the Hverfjall eruptive fissure, north Iceland: eruption chronology and resulting deposits. J Volcanol Geotherm Res 201:241–252. doi:10.1016/j.jvolgeores.2010.05.015

    Article  Google Scholar 

  • Nakamura K (1977) Volcanoes as possible indicators of tectonic stress orientation—principle and proposal. J Volcanol Geotherm Res 2:1–16. doi:10.1016/0377-0273(77)90012-9

    Article  Google Scholar 

  • Opheim JA, Guðmundsson Á (1989) Formation and geometry of fractures, and related volcanism, of the Krafla fissure swarm, northeast Iceland. Geol Soc Am Bull 101:1608–1622. doi:10.1130/0016-7606(1989) 101<1608:FAGOFA>2.3.CO;2

    Article  Google Scholar 

  • Paquet F, Dauteuil O, Hallot E, Moreau F (2007) Tectonics and magma dynamics coupling in a dyke swarm of Iceland. J Struct Geol 29:1477–1493. doi:10.1016/j.jsg.2007.06.001

    Article  Google Scholar 

  • Rowland JV, Baker E, Ebinger CJ, Keir D, Kidane T, Biggs J, Hayward N, Wright TJ (2007) Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar. Geophys J Int 171:1226–1246. doi:10.1111/j.1365-246X.2007.03584.x

    Article  Google Scholar 

  • Rubin AM (1992) Dike-induced faulting and graben subsidence in volcanic rift zones. J Geophys Res Solid Earth 97:1839–1858. doi:10.1029/91JB02170

    Article  Google Scholar 

  • Sigmundsson F (2006) Iceland geodynamics, crustal deformation and divergent plate tectonics. Praxis, Chichester

    Google Scholar 

  • Sigurðsson H, Sparks SRJ (1978) Rifting episode in North Iceland in 1874–1875 and the eruptions of Askja and Sveinagja. Bull Volcanol 41:149–167. doi:10.1007/BF02597219

    Article  Google Scholar 

  • Sigurðsson O (1980) Surface deformation of the Krafla fissure swarm in two rifting events. J Geophys 47:154–159

    Google Scholar 

  • Stefánsson R, Guðmundsson GB, Halldórsson P (2008) Tjörnes fracture zone. New and old seismic evidences for the link between the North Iceland rift zone and the Mid-Atlantic ridge. Tectonophysics 447:117–126. doi:10.1016/j.tecto.2006.09.019

    Article  Google Scholar 

  • Sæmundsson J (1730) Sandferdig Relation om det udi Island Brændenda Field Krabla, og andre der omkring liggende Smaae Fielde, baade med Jordskielv. In: Torden and Askefald, Kopenhagen, Denmark, p 2

  • Sæmundsson K (1973) Straumrákaðar klappir í kringum Ásbyrgi. Náttúrufræðingurinn 43:52–60 (in Icelandic)

    Google Scholar 

  • Sæmundsson K (1974) Evolution of the axial rifting zone on Northern Iceland and the Tjörnes Fracture Zone. Geol Soc Am Bull 85:495–504. doi:10.1130/0016-7606(1974) 85<495:EOTARZ>2.0.CO;2

    Article  Google Scholar 

  • Sæmundsson K (1977) Geological map of Iceland Sheet 7 North East Iceland. Iceland Geodetic Survey and the Museum of Natural History, Reykjavík

  • Sæmundsson K (1991) Jarðfræði Kröflukerfisins (in Icelandic). In: Garðarsson A, Einarsson Á (eds) Náttúra Mývatns. Icelandic Nature Sci Soc, Reykjavík, pp 24–95

    Google Scholar 

  • Tilling RI, Dvorak JJ (1993) Anatomy of a basaltic volcano. Nature 363:125–133. doi:10.1038/363125a0

    Article  Google Scholar 

  • Tolstoy M, Cowen JP, Baker ET, Fornari DJ, Rubin KH, Shank TM, Waldhauser F, Bohnenstiehl DR, Forsyth DW, Holmes RC, Love B, Perfit MR, Weekly RT, Soule SA, Glazer B (2006) A sea-floor spreading event captured by seismometers. Science 314:1920–1922. doi:10.1126/science.1133950

    Article  Google Scholar 

  • Tryggvason E (1986) Multiple magma reservoirs in a rift-zone volcano–ground deformation and magma transport during the September 1984 eruption of Krafla, Iceland. J Volcanol Geotherm Res 28:1–44. doi:10.1016/0377-0273(86)90003-X

    Article  Google Scholar 

  • Walker GPL (1958) Geology of the Reydarfjördur area, Eastern Iceland. Q J Geol Soc 114:367–391. doi:10.1144/gsjgs.114.1.0367

    Article  Google Scholar 

  • Walker GPL (1960) Zeolite zones and dike distribution in relation to the structure of the basalts of eastern Iceland. J Geol 515–528

  • White RS, Drew J, Martens HR, Key J, Soosalu H, Jakobsdóttir SS (2011) Dynamics of dyke intrusion in the mid-crust of Iceland. Earth Planet Sci Lett 304:300–312. doi:10.1016/j.epsl.2011.02.038

    Article  Google Scholar 

  • Wright TJ, Ebinger C, Biggs J, Ayele A, Yirgu G, Keir D, Stork A (2006) Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode. Nature 442:291–294. doi:10.1038/nature04978

    Article  Google Scholar 

  • Wright TJ, Sigmundsson F, Ayele A, Belachew M, Brandsdóttir B, Calais E, Ebinger C, Einarsson P, Hamling I, Keir D, Lewi E, Pagli C, Pedersen R (2012) Geophysical constraints on the dynamics of spreading centres from rifting episodes on land. Nat Geosci 5:242–250. doi:10.1038/NGEO1428

    Article  Google Scholar 

  • Þórarinsson S (1951) Laxárgljúfur and Laxárhraun: a tephrochronological study. Geogr Ann 33:1–89

    Article  Google Scholar 

  • Þórarinsson S (1979) The postglacial history of the Mývatn area. Oikos 32:17–28

    Article  Google Scholar 

  • Þórarinsson S, Sigvaldason GE (1962) The eruption in Askja, 1961: a preliminary report. Am J Sci 260:641–651. doi:10.2475/ajs.260.9.641

    Article  Google Scholar 

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Acknowledgements

We would like to express our gratitude to Fróði Jones and Sigríður Magnúsdóttir for their assistance and companionship during the fieldwork. Kristján Sæmundsson and Bryndís Brandsdóttir gave valuable comments on the paper. Bryndís also provided the earthquake data from the Krafla rifting episode. In addition, we would like to thank the Vatnajökulsþjóðgarður National Park and its staff in Jökulsárgljúfur for assistance during the fieldwork. The paper was improved considerably in response to comments by the editor and the reviewers of this paper; Þorvaldur Þórðarson, Maryam Khodayar, Steffi Burchardt and an anonymous reviewer.

The project was supported by a grant from the Icelandic Centre for Research and the University of Iceland Research Fund to Ásta Rut Hjartardóttir and Páll Einarsson. Acquisition and analysis of airborne LiDAR data is supported by the UK Natural Environment Research Council through their Airborne Research and Survey Facility and a studentship for Emma Bramham. Tim J. Wright is supported by a Royal Society University Research Fellowship.

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  1. Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, 101, Reykjavík, Iceland

    Ásta Rut Hjartardóttir & Páll Einarsson

  2. School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, W Yorkshire, UK

    Emma Bramham & Tim J. Wright

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  1. Ásta Rut Hjartardóttir
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Correspondence to Páll Einarsson.

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Hjartardóttir, Á.R., Einarsson, P., Bramham, E. et al. The Krafla fissure swarm, Iceland, and its formation by rifting events. Bull Volcanol 74, 2139–2153 (2012). https://doi.org/10.1007/s00445-012-0659-0

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