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SUMMARY:Volcano geodesy and plate boundary deformation in Iceland - Prof F
 reysteinn Sigmundsson\,  Nordic Volcanological Centre
DTSTART:20170118T160000Z
DTEND:20170118T170000Z
UID:TALK70174@talks.cam.ac.uk
CONTACT:David Al-Attar
DESCRIPTION:The details of plate spreading and surface movements on volcan
 oes in Iceland has been mapped with GPS-geodesy and interferometric analys
 is of synthetic aperture radar images acquired by satellites (InSAR). Thes
 e data allow constraints on mechanical models of pate spreading and how vo
 lcanoes work. Observed deformation reflects processes in persistent magma 
 domains under a number of volcanoes\, at a depth ranging from 2-20 km. The
  plate boundary is simplest in N-Iceland\, where GPS studies have revealed
  how strain and stress builds up in an approximately 50 km wide zone\, due
  to 18 mm/yr plate spreading. Despite the en-echelon arranged fissure swar
 ms\, we find a single zone of current stretching with an axis crossing the
  central volcanoes with most recent activity. By considering the combined 
 effects of plate boundary and topography related stress fields\, as well a
 s change in gravitational energy\, a model can developed to forecast the p
 ath of laterally propagating dykes. The model can explain the observed hig
 hly segmented geometry of a 50-km long dyke that formed in the Bárðarbun
 ga volcanic system\, during a period of major activity 2014-2015. The dyke
  provided a magma flow path linking a major lava eruption in the Holuhraun
  plain north of Vatnajökull (about 1.5 km3) and a gradual caldera collaps
 e of the ice covered Bárðarbunga caldera (about 65 m). \n\nReference:\n\
 nSigmundsson\, F.\, Hooper\, A. Hreinsdottir\, S.\, Vogfjord\, K.S.\,  Ofe
 igsson\, B.G.\, Heimisson\, E.R.\, Dumont\, S.\, Parks\, M.\, Spaans\, K.\
 , Gudmundsson\, G.B.\, Drouin\, V.\, + 26 others (2015)\, Segmented latera
 l dyke growth in a rifting event at Bardarbunga volcanic system\, Iceland\
 , Nature\, 517(7533)\, 191–195\, doi:10.1038/nature14111.
\n\nHeimisso
 n\, E. R.\, A. Hooper\, and
F. Sigmundsson (2015)\, Forecasting the path
  of a laterally propagating dike\, J. Geophys. Res. Solid Earth\, 120\, do
 i:10.1002/2015JB012402. 
\n\nGudmundsson\, M.T.\, Jónsdóttir\, K.\, Ho
 oper\, A.\, Holohan\, E. P.\, Halldórsson\, S.A.\, Ófeigsson\, B.G.\, Ce
 sca\, S.\,Vogfjörd\, K.S\, Sigmundsson\, F.\, Högnadóttir\, Th.\, Einar
 sson\, P. + 37 others (2016)\, Gradual caldera collapse at Bárdarbunga vo
 lcano\, Iceland\, regulated by lateral magma outflow\, Science\, 15 July 2
 016\, vol. 353\, issue 6296\, aaf8988. DOI: 10.1126/science.aaf8988.\n
LOCATION:Marine/Wolfson Building lecture hall\, Bullard Labs.
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