E. Sturkell et al. / Journal of <strong>Volcano</strong>logy <strong>and</strong> Geothermal Research 150 (2006) 14–34 33Kjartansson, E., Grönvold, K., 1983. Location of a <strong>magma</strong> reservoirbeneath Hekla volcano, Icel<strong>and</strong>. Nature 301, 139–141.Larsen, G., 1984. Recent volcanic history of the Veiðivötn fissureswarm, southern Icel<strong>and</strong>: an approach to volcanic risk assessment.J. <strong>Volcano</strong>l. Geotherm. Res. 22, 33–58.Larsen, G., 1999. Gosið í Eyjafjallajökli 1821–23. Rep. RH-28-99,Science Institute, University of Icel<strong>and</strong>. 13 pp.Larsen, G., 2000. Holocene eruptions with<strong>in</strong> the Katla volcanicsystem, south Icel<strong>and</strong>: characteristics <strong>and</strong> environmental impact.Jökull 49, 1 –28.L<strong>in</strong>de, A.T., Agustsson, K., Sacks, I.S., Stefansson, R., 1993.Mechanism of the 1991 eruption of Hekla from cont<strong>in</strong>uousborehole stra<strong>in</strong> monitor<strong>in</strong>g. Nature 365, 737–740.Massonnet, D., Feigl, K.L., 1998. Radar Interferometry <strong>and</strong> itsapplication to changes <strong>in</strong> the Earth’s surface. Rev. Geophys.36, 441–500.McGarvie, D.W., 1984. Torfajökull: a volcano dom<strong>in</strong>ated by<strong>magma</strong> mix<strong>in</strong>g. Geology 12, 685–688.Mogi, K., 1958. Relations between the eruptions of various volcanoes<strong>and</strong> the deformation of the ground surface around them.Bull. Earthquake Res. Inst. Univ. Tokyo 36, 99–134.Pagli, C., Sigmundsson, F., Árnadóttir, Th., E<strong>in</strong>arsson, P., 2003.Subsidence of Askja volcano, north Icel<strong>and</strong>: InSAR observations<strong>and</strong> different model<strong>in</strong>g approaches. Eos Trans AGU FallMeet Suppl. Abstr., vol. V22A-0561, pp. F1520.Pedersen, P., Sigmundsson, F., 2004. InSAR based sill model l<strong>in</strong>ksspatially offset areas of deformation <strong>and</strong> seismicity for the 1994unrest episode at Eyjafjallajökull volcano. Geophys. Res. Lett.31, L14610. doi:10.1029/2004GL020368.Pedersen, R., Jónsson, S., Árnadóttir, Th., Sigmundsson, F., Feigl,K.L., 2003. Fault slip distribution of two June 2000 Mw 6.5 earthquakes<strong>in</strong> South Icel<strong>and</strong> estimated from jo<strong>in</strong>t <strong>in</strong>version of InSAR <strong>and</strong>GPS measurements. Earth Planet. Sci. Lett. 213, 487–502.Pollitz, F.F., Sacks, I.S., 1996. Viscosity structure beneath northeastIcel<strong>and</strong>. J. Geophys. Res 101, 17771–17793.Rist, S., 1967. Jökulhlaups from the ice cover of Mýrdalsjökull onJune 25, 1955 <strong>and</strong> January 20, 1956. Jökull 17, 243–248.Roberts, M.J., Tweed, F.S., Russell, A.J., Knudsen, Ó., Harris, T.D.,2003. Hydrological <strong>and</strong> geomorphic effects of temporary icedammedlake formation dur<strong>in</strong>g jökulhlaups. Earth Surf. ProcessesL<strong>and</strong>f. 28, 723–737.Rymer, H., 1996. Microgravity monitor<strong>in</strong>g. Monitor<strong>in</strong>g <strong>and</strong>Mitigation of <strong>Volcano</strong> Hazards. Spr<strong>in</strong>ger-Verslag, Berl<strong>in</strong>,pp. 169–198.Rymer, H., Tryggvason, E., 1993. Gravity <strong>and</strong> elevation changes atAskja, Icel<strong>and</strong>. Bull. <strong>Volcano</strong>l. 55, 362–371.Rymer, H., Cassidy, J., Locke, C.A., Sigmundsson, F., 1998. Posteruptivegravity changes from 1990 to 1996 at Krafla volcano,Icel<strong>and</strong>. J. <strong>Volcano</strong>l. Geotherm. Res. 87, 141–149.Sacks, I.S., Suyehiro, S., Everton, D.W., Yamagishi, Y., 1971.Sacks–Evertson stra<strong>in</strong>meter, its <strong>in</strong>stallation <strong>in</strong> Japan <strong>and</strong> someprelim<strong>in</strong>ary results concern<strong>in</strong>g stra<strong>in</strong> steps. Pap. Meteorol. Geophys.22, 195–207.Sigmarsson, O., Karlsson, H.R., Larsen, G., 2000. The 1996 <strong>and</strong>1998 subglacial eruptions beneath the Vatnajökull ice sheet <strong>in</strong>Icel<strong>and</strong>: contrast<strong>in</strong>g geochemical <strong>and</strong> geophysical <strong>in</strong>ferences on<strong>magma</strong> migration. Bull. <strong>Volcano</strong>l. 61, 468–476.Sigmundsson, F., E<strong>in</strong>arsson, P., Bilham, R., 1992. Magma chamberdeflation recorded by the Global Position<strong>in</strong>g System; the Hekla1991 eruption. Geophys. Res. Lett. 19, 1483–1486.Sigmundsson, F., Vadon, H., Massonet, D., 1997. Readjustmentof the Krafla spread<strong>in</strong>g segment to crustal rift<strong>in</strong>g measuredby Satellite Radar Interferometry. Geophys. Res. Lett. 24,1843–1846.Sigmundsson, F., E<strong>in</strong>arsson, P., Rögnvaldsson, S., Foulger, G.R.,Hodgk<strong>in</strong>son, K.M., 1997. The 1994–1995 seismicity <strong>and</strong> deformationat the Hengill triple junction, Icel<strong>and</strong>: trigger<strong>in</strong>g ofearthquakes by m<strong>in</strong>or <strong>magma</strong> <strong>in</strong>jection <strong>in</strong> a zone of horizontalshear stress. J. Geophys. Res. 102, 15151–15161.Sigmundsson, F., Pedersen, R., Feigl, K., Sturkell, E., E<strong>in</strong>arsson,P., Jonsson, S., Agustsson, K., L<strong>in</strong>de, A., Bretar, F., 2001.Jo<strong>in</strong>t <strong>in</strong>terpretation of geodetic data for volcano studies: evaluationof pre- <strong>and</strong> co-eruptive deformation for the Hekla 2000eruption from InSAR, tilt, GPS <strong>and</strong> stra<strong>in</strong> data. Eos. Trans.AGU, 82, Fall. Meet. Suppl., Abstr., vol. V21E-E07.Sigurdsson, O., 1980. Surface deformation of the Krafla fissureswarm <strong>in</strong> two rift<strong>in</strong>g events. J. Geophys. 47, 154–159.Sigurðsson, O., Zóphoníasson, S., Ísleifsson, E., 2000. The jökulhlaupfrom Sólheimajökull July 18th 1999 (Jökulhlaup úr Sólheimajökli18. júlí 1999, <strong>in</strong> Icel<strong>and</strong>ic with English summary).Jökull 49, 75–80.Slunga, R., 1991. Earthquake source mechanism determ<strong>in</strong>ation byuse of body-wave amplitudes— an application to Swedish earthquakes.Bull. Seismol. Soc. Am. 71, 25–35.Soosalu, H., E<strong>in</strong>arsson, P., 1997. Seismicity around the Hekla <strong>and</strong>Torfajökull volcanoes, Icel<strong>and</strong>, dur<strong>in</strong>g a volcanically quiet period,1991–1995. J. <strong>Volcano</strong>l. 59, 36–48.Soosalu, H., E<strong>in</strong>arsson, P., 2004. Seismic constra<strong>in</strong>ts on <strong>magma</strong>chambers at Hekla <strong>and</strong> Torfajökull volcanoes, Icel<strong>and</strong>. Bull.<strong>Volcano</strong>l. 66, 276–286.Soosalu, H., E<strong>in</strong>arsson, P., þorbjarnardóttir. B., <strong>in</strong> press. Seismicactivity associated with the 2000 eruption of Hekla, Icel<strong>and</strong>.Bull. Volc. (Published on l<strong>in</strong>e ahead of pr<strong>in</strong>t, doi:10.1007/s00445-005-0417-7).Soosalu, H., Jónsdóttir, K., E<strong>in</strong>arsson, P. submitted for publication.Seismicity crisis at the Katla volcano. Icel<strong>and</strong> — signs of acryptodome? submitted.Sturkell, E., Sigmundsson, F., 2000. Cont<strong>in</strong>uous deflation of theAskja caldera Icel<strong>and</strong>, dur<strong>in</strong>g the 1983–1998 non-eruptiveperiod. J. Geophys. Res. 105, 25671–25684.Sturkell, E., E<strong>in</strong>arsson, P., Sigmundsson, P., Hre<strong>in</strong>sdottir, F., Geirsson,S., 2003a. Deformation of Grímsvötn volcano, Icel<strong>and</strong> :1998eruption <strong>and</strong> subsequent <strong>in</strong>flation. Geophys. Res. Lett. 30, 1182.doi:10.129/2002GL016460.Sturkell, E., Sigmundsson, F., E<strong>in</strong>arsson, P., 2003b. Recent unrest<strong>and</strong> <strong>magma</strong> movements at Eyjafjallajökull <strong>and</strong> Katla volcanoes,Icel<strong>and</strong>. J. Geophys. Res. 108 (B8), 2369. doi:10.1029/2001JB000917.Sturkell, E., Sigmundsson, F., E<strong>in</strong>arsson, P., Geirsson, H., Roberts,M.J., 2003c. Magma <strong>in</strong>flow <strong>in</strong>to Katla, one of Icel<strong>and</strong>’s mosthazardous volcanoes. Eos Trans. AGU, Fall Meet Suppl., Abstr.,vol. V12G-07, pp. F1503.Sturkell, E., Sigmundsson, F., Slunga, R., submitted for publication.1983–2003 decay<strong>in</strong>g rate of deflation at Askja caldera: pressure
34E. Sturkell et al. / Journal of <strong>Volcano</strong>logy <strong>and</strong> Geothermal Research 150 (2006) 14–34decrease <strong>in</strong> an extensive <strong>magma</strong> plumb<strong>in</strong>g system at a spread<strong>in</strong>gplate boundary. Bull. <strong>Volcano</strong>l.Tryggvason, E., 1980. Subsidence events <strong>in</strong> the Krafla area, NorthIcel<strong>and</strong>,1975–1979. J. Geophys. 47, 141–153.Tryggvason, E., 1986. Multiple <strong>magma</strong> reservoirs <strong>in</strong> a rift zonevolcano: ground deformation <strong>and</strong> <strong>magma</strong> transport dur<strong>in</strong>g theSeptember 1984 eruption of Krafla, Icel<strong>and</strong>. J. <strong>Volcano</strong>l.Geotherm. Res. 28, 1 –44.Tryggvason, E., 1987. Myvatn lake level observations 1984–1986<strong>and</strong> ground deformation dur<strong>in</strong>g a Krafla eruption. J. <strong>Volcano</strong>l.Geotherm. Res. 31, 131–138.Tryggvason, E., 1989. Ground deformation <strong>in</strong> Askja, Icel<strong>and</strong>: itssource <strong>and</strong> possible relation to flow of the mantle plume.J. <strong>Volcano</strong>l. Geotherm. Res. 39, 61–71.Tryggvason, E., 1994. Observed ground deformation at Hekla, Icel<strong>and</strong>prior to <strong>and</strong> dur<strong>in</strong>g the eruptions of 1970, 1980–1981 <strong>and</strong>1991. J. <strong>Volcano</strong>l. Geotherm. Res. 61, 281–291.Tryggvason, E., 1995. Optical levell<strong>in</strong>g tilt stations <strong>in</strong> thevic<strong>in</strong>ity of Krafla <strong>and</strong> the Krafla fissure swarm. Observations1976 to 1994, vol. 9505. Nordic <strong>Volcano</strong>l. Inst, Reykjavík,Rep, pp. 218.Vadon, H., Sigmundsson, F., 1997. Crustal deformation from 1992to 1995 at the mid-Atlantic Ridge, Southwest Icel<strong>and</strong>, Mappedby Satellite Radar Interferometry. Science 275, 193–197.Vogfjörd, K.S., Jakobsdóttir, S.S., Gudmundsson, G.B., Roberts,M.J., Ágústsson, K., Arason, T., Geirsson, H., Karlsdóttir, S.Hjaltadóttir, S., Ólafsdóttir, U., Thorbjarnardóttir, B., Skaftadóttir,T., Sturkell, E., Jónasdóttir, E.B., Hafste<strong>in</strong>sson, G.,Sve<strong>in</strong>bjórnsson, H., Stefánsson, R., Jónsson T.V., 2005. Forecast<strong>in</strong>g<strong>and</strong> Monitor<strong>in</strong>g a Subglacial Eruption <strong>in</strong> Icel<strong>and</strong>, EOS86, 245, 248.Wolfe, C.J., Bjarnason, I.Th., VanDecar, J.C., Solomon, S.C., 1997.Seismic structure of the Icel<strong>and</strong> mantle plume. Nature 385,245–247.