| Summary: | Lying below Vatnajökull ice cap in Iceland, Bárðarbunga stratovolcano began experiencing wholesale caldera collapse in 2014 August 16, one of the largest such events recorded in the modern instrumental era. Simultaneous with this collapse is the initiation of a plate boundary rifting episode north of the caldera. Observations using the international constellation of radar satellites indicate rapid 50 cm d^(−1) subsidence of the glacier surface overlying the collapsing caldera and metre-scale crustal deformation in the active rift zone. Anomalous earthquakes around the rim of the caldera with highly nondouble-couple focal mechanisms provide a mechanical link to the dynamics of the collapsing magma chamber. A model of the collapse consistent with available geodetic and seismic observations suggests that the majority of the observed subsidence occurs aseismically via a deflating sill-like magma chamber. © The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society. Accepted 2015 April 8. Received 2015 April 2. In original form 2015 January 21. We thank Egill Hauksson and Hilary Martens for discussions in the early phase of this study. We also thank Agust Gudmundsson, Jürg Schuler and three anonymous reviewers for their helpful comments and for improving the quality of this manuscript. BR was supported under a National Aeronautics and Space Administration (NASA) Earth and Space Science Fellowship. Part of this research was carried out at the Jet Propulsion Laboratory and the California Institute of Technology under a contract with NASA and funded through the President's and Director's Fund Program. This research was carried out using COSMO-SkyMed (CSK ®) products delivered under an Italian Space Agency (ASI) license and is made possible through a collaboration between JPL/Caltech/CIDOT and NASA/ASI. Published - Geophys._J._Int.-2015-Riel-446-53.pdf Supplemental Material - supp_Bardarbunga_GJI.pdf
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