<\/p>\n
Sprungur og sprungusveimar \u00e1 \u00cdslandi<\/strong><\/p>\n \u00cdsland liggur \u00e1 flekaskilum Nor\u00f0ur-Amer\u00edku og Evras\u00eduflekans. Flekarnir reka hver \u00ed s\u00edna \u00e1ttina um 9,7 mm \u00e1 \u00e1ri, samtals um 19, 4 mm \u00e1 \u00e1ri (\u00c1rnad\u00f3ttir et al., 2009). \u00c1 flekam\u00f3tunum ver\u00f0a til sprungur \u00feegar flekana rekur \u00ed sundur e\u00f0a me\u00f0fram hvor \u00f6\u00f0rum. Til a\u00f0 auka a\u00f0eins \u00e1 fl\u00e6kjuna m\u00e1 skilgreina \u00feri\u00f0ja flekann, Hreppaflekann, sem er sm\u00e1fleki \u00e1 su\u00f0urhluta landsins (Einarsson, 2008).<\/p>\n E\u00f0li \u00feessara sprungna er alla jafna misjafnt eftir \u00fev\u00ed hvar \u00fe\u00e6r eru. \u00deannig myndast siggengi og togsprungur \u00fear sem fleka rekur \u00ed sundur, en \u00fear sem hreyfingin er sams\u00ed\u00f0a sprungunum (fleka rekur me\u00f0fram hvor \u00f6\u00f0rum), \u00fear myndast sni\u00f0gengissprungur. Stundum eru sprungurnar \u00ed raun samspil \u00feessara \u00fe\u00e1tta og bera einkenni \u00feeirra beggja. Erlendis er auk \u00feess algengt a\u00f0 finna samgengissprungur, \u00fear sem fleka rekur saman, en \u00fea\u00f0 er mj\u00f6g sjaldg\u00e6ft a\u00f0 finna sl\u00edkar sprungur h\u00e9r \u00e1 landi og m\u00e1 \u00ed raun bara finna sta\u00f0bundi\u00f0, \u00fear sem jar\u00f0skorpa hefur k\u00fdst eil\u00edti\u00f0 saman.<\/p>\n Sprungusveimar<\/strong><\/p>\n Sprungusveimar \u00e1 \u00cdslandi finnast \u00fear sem fleka rekur \u00ed sundur, \u00e1 fr\u00e1reksbeltum (Hjartard\u00f3ttir and Einarsson, 2017; Hjartard\u00f3ttir et al., 2016a; Hjartard\u00f3ttir et al., 2016c; S\u00e6mundsson, 1974). Sprungusveimar eru \u00ed raun bara sv\u00e6\u00f0i \u00fear sem miki\u00f0 er af sprungum og gossprungum. Oft eru sprungusveimar me\u00f0 megineldst\u00f6\u00f0. \u00dear er mesta eldvirknin \u00e1 sv\u00e6\u00f0inu, en \u00fe\u00f3 m\u00e1 finna gossprungur v\u00ed\u00f0a \u00e1 sprungusveimum. \u00cd lj\u00f3s hefur komi\u00f0 a\u00f0 sprungur \u00ed sprungusveimum \u00e1 \u00cdslandi vir\u00f0ast a\u00f0allega myndast \u00ed tengslum vi\u00f0 eldvirkni. \u00deetta s\u00e1st til d\u00e6mis sk\u00fdrt \u00e1ri\u00f0 2014, \u00feegar gangainnskot skaust fr\u00e1 B\u00e1r\u00f0arbungu og allt a\u00f0 (gamla) Holuhrauni (Sigmundsson et al., 2015). Eftir a\u00f0 gangainnskoti\u00f0 komst nor\u00f0ur fyrir Vatnaj\u00f6kul s\u00e1ust n\u00fdjar sprungur \u00e1 yfirbor\u00f0i gamla Holuhraunsins. \u00deessar sprungur m\u00f6rku\u00f0u sigdal. Sigdalurinn var ekki brei\u00f0ur, um 1 km a\u00f0 breidd sunnan til og einungis um 250-450 m brei\u00f0ur nor\u00f0an til. \u00deessi mj\u00f3i sigdalur benti til \u00feess a\u00f0 kvikan v\u00e6ri \u00e1 mj\u00f6g litlu d\u00fdpi. N\u00fdju sprungurnar s\u00e1ust \u00feann 27.\u00e1g\u00fast 2014. Tveimur d\u00f6gum s\u00ed\u00f0ar h\u00f3fst eldgos, sem \u00e1tti s\u00e9r uppt\u00f6k innan sigdalsins, eins og vi\u00f0 m\u00e1tti b\u00faast (Hjartard\u00f3ttir et al., 2016b).<\/p>\n Svipa\u00f0a heg\u00f0un m\u00e1tti einnig sj\u00e1 \u00feegar Kr\u00f6flueldar \u00e1ttu s\u00e9r sta\u00f0 \u00e1 \u00e1runum 1975 til 1984. \u00de\u00e1 \u00e1ttu \u00edtreku\u00f0 gangainnskot s\u00e9r sta\u00f0, \u00fear sem gangar skutust anna\u00f0 hvort til nor\u00f0urs e\u00f0a su\u00f0urs fr\u00e1 megineldst\u00f6\u00f0inni Kr\u00f6flu (Einarsson, 1991; Sigurdsson, 1980).<\/p>\n \u00deverbrotabelti<\/strong><\/p>\n \u00c1 \u00feverbrotabeltum geta jar\u00f0skj\u00e1lftar or\u00f0i\u00f0 st\u00e6rri en annars sta\u00f0ar \u00e1 flekaskilunum \u00e1 \u00cdslandi. \u00c1 \u00cdslandi eru tv\u00f6 \u00feverbrotabelti, Su\u00f0urlandsskj\u00e1lftabelti\u00f0 og Tj\u00f6rnesbrotabelti\u00f0 (Einarsson, 2008; Einarsson, 2010). \u00dea\u00f0 s\u00ed\u00f0arnefnda samanstendur af \u00feremur brotabeltum, Gr\u00edmseyjarbeltinu, H\u00fasav\u00edkurmisgenginu og Dalv\u00edkurbeltinu. \u00c1 \u00feessum sv\u00e6\u00f0um ver\u00f0a jar\u00f0skj\u00e1lftar allt a\u00f0 6 til 7 stig a\u00f0 st\u00e6r\u00f0 (Stef\u00e1nsson et al., 2008).<\/p>\n <\/p>\n Heimildir<\/strong><\/p>\n \u00c1rnad\u00f3ttir, T., Lund, B., Jiang, W., Geirsson, H., Bj\u00f6rnsson, H., Einarsson, P. and Sigur\u00f0sson, T., 2009. Glacial rebound and plate spreading: results from the first countrywide GPS observations in Iceland. Geophys J Int, 177(2): 691-716.<\/p>\n Einarsson, P., 1991. Umbrotin vi\u00f0 Kr\u00f6flu 1975-1989. In: A. Gar\u00f0arsson and \u00c1. Einarsson (Editors), N\u00e1tt\u00fara M\u00fdvatns. Hi\u00f0 \u00edslenska n\u00e1tt\u00farufr\u00e6\u00f0if\u00e9lag, Reykjav\u00edk, pp. 97-139.<\/p>\n Einarsson, P., 2008. Plate boundaries, rifts and transforms in Iceland. J\u00f6kull, 58: 35-58.<\/p>\n Einarsson, P., 2010. Mapping of Holocene surface ruptures in the South Iceland Seismic Zone. J\u00f6kull, 60: 117-134.<\/p>\n Hjartard\u00f3ttir, \u00c1.R. and Einarsson, P., 2017. Sprungusveimar Nor\u00f0urgosbeltisins og umbrotin \u00ed B\u00e1r\u00f0arbungu 2014-2015. N\u00e1tt\u00farufr\u00e6\u00f0ingurinn, 87(1-2): 24-39.<\/p>\n Hjartard\u00f3ttir, \u00c1.R., Einarsson, P. and Bj\u00f6rgvinsd\u00f3ttir, S., 2016a. Fissure swarms and fracture systems within the Western Volcanic Zone, Iceland \u2013 effects of spreading rates. J Struct Geol, 91: 39-53.<\/p>\n Hjartard\u00f3ttir, \u00c1.R., Einarsson, P., Gudmundsson, M.T. and H\u00f6gnad\u00f3ttir, T., 2016b. Fracture movements and graben subsidence during the 2014 B\u00e1r\u00f0arbunga dike intrusion in Iceland. J Volcanol Geotherm Res, 310: 242-252.<\/p>\n Hjartard\u00f3ttir, \u00c1.R., Einarsson, P., Magn\u00fasd\u00f3ttir, S., Bj\u00f6rnsd\u00f3ttir, \u00de. and Brandsd\u00f3ttir, B., 2016c. Fracture systems of the Northern Volcanic Rift Zone, Iceland - an onshore part of the Mid-Atlantic plate boundary. In: T.J. Wright, A. Ayele, D.J. Ferguson, T. Kidane and C. Vye-Brown (Editors), Magmatic Rifting and Active Volcanism. The Geological Society of London, pp. 297-314.<\/p>\n Sigmundsson, F., Hooper, A., Hreinsdottir, S., Vogfjord, K.S., Ofeigsson, B.G., Heimisson, E.R., Dumont, S., Parks, M., Spaans, K., Gudmundsson, G.B., Drouin, V., Arnadottir, T., Jonsdottir, K., Gudmundsson, M.T., Hognadottir, T., Fridriksdottir, H.M., Hensch, M., Einarsson, P., Magnusson, E., Samsonov, S., Brandsdottir, B., White, R.S., Agustsdottir, T., Greenfield, T., Green, R.G., Hjartardottir, A.R., Pedersen, R., Bennett, R.A., Geirsson, H., La Femina, P.C., Bjornsson, H., Palsson, F., Sturkell, E., Bean, C.J., Mollhoff, M., Braiden, A.K. and Eibl, E.P.S., 2015. Segmented lateral dyke growth in a rifting event at Bardarbunga volcanic system, Iceland. Nature, 517(7533): 191-195.<\/p>\n Sigurdsson, O., 1980. Surface deformation of the Krafla fissure swarm in two rifting events. Journal of Geophysics-Zeitschrift Fur Geophysik, 47(1-3): 154-159.<\/p>\n Stef\u00e1nsson, R., Gu\u00f0mundsson, G.B. and Halld\u00f3rsson, P., 2008. Tj\u00f6rnes fracture zone. New and old seismic evidences for the link between the North Iceland rift zone and the Mid-Atlantic ridge. Tectonophysics, 447(1-4): 117-126.<\/p>\n S\u00e6mundsson, K., 1974. Evolution of the axial rifting zone on Northern Iceland and the Tj\u00f6rnes Fracture Zone. Geol Soc Am Bull, 85: 495-504.<\/p>\n <\/p>","protected":false},"excerpt":{"rendered":" Sprungur og sprungusveimar \u00e1 \u00cdslandi \u00cdsland liggur \u00e1 flekaskilum Nor\u00f0ur-Amer\u00edku og Evras\u00eduflekans. Flekarnir reka hver \u00ed s\u00edna \u00e1ttina um 9,7 mm \u00e1 \u00e1ri, samtals um 19, 4 mm \u00e1 \u00e1ri (\u00c1rnad\u00f3ttir et al., 2009). \u00c1 flekam\u00f3tunum ver\u00f0a til sprungur \u00feegar flekana rekur \u00ed sundur e\u00f0a me\u00f0fram hvor \u00f6\u00f0rum. Til a\u00f0 auka a\u00f0eins \u00e1 fl\u00e6kjuna … <\/p>\n