Abstract

The details of plate spreading and surface movements on volcanoes in Iceland has been mapped with GPS -geodesy and interferometric analysis of synthetic aperture radar images acquired by satellites (InSAR). These data allow constraints on mechanical models of pate spreading and how volcanoes 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 swarms, 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 as change in gravitational energy, a model can developed to forecast the path of laterally propagating dykes. The model can explain the observed highly segmented geometry of a 50-km long dyke that formed in the Bárðarbunga 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 collapse of the ice covered Bárðarbunga caldera (about 65 m).

Reference:

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., + 26 others (2015), Segmented lateral dyke growth in a rifting event at Bardarbunga volcanic system, Iceland, Nature, 517(7533), 191–195, doi:10.1038/nature14111.


Heimisson, E. R., A. Hooper, and
F. Sigmundsson (2015), Forecasting the path of a laterally propagating dike, J. Geophys. Res. Solid Earth, 120, doi:10.1002/2015JB012402. 


Gudmundsson, M.T., Jónsdóttir, K., Hooper, A., Holohan, E. P., Halldórsson, S.A., Ófeigsson, B.G., Cesca, S.,Vogfjörd, K.S, Sigmundsson, F., Högnadóttir, Th., Einarsson, P. + 37 others (2016), Gradual caldera collapse at Bárdarbunga volcano, Iceland, regulated by lateral magma outflow, Science, 15 July 2016, vol. 353, issue 6296, aaf8988. DOI : 10.1126/science.aaf8988.