| Summary: | Post-eruptive deformation following volcanic eruptions may originate from continued magma movements, or reflect delayed and continued Earth adjustment due to co-eruptive events, often referred to as viscoelastic relaxation. Post-eruptive deformation can continue for years, and it is challenging to reveal the details of the underlying processes. In this PhD project, the ground deformation in a post-eruptive period at the Bárðarbunga volcanic system is mapped using Global Navigation Satellite System (GNSS) geodesy and Interferometric analysis of Synthetic Aperture Radar satellite images (InSAR). The Bárðarbunga volcanic system is a laboratory area for this study because of the large-scale magma transfer during an eruption in 2014-2015, lasting six months. Magma flowed laterally along a 48-km-long dike from a magma body below the Bárðarbunga caldera. An eruption occurred at the northern end of the dike. During this time, the Bárðarbunga caldera collapsed 65 m. Data collected using GNSS and InSAR techniques provide information on the post-rifting ground deformation both in the area near the Bárðarbunga caldera and the northernmost segment of the Bárðarbunga-Holuhraun dike north of the Vatnajökull ice cap. The background deformation signal in the area includes plate spreading (18-19 mm/yr in the horizontal direction) and glacial isostatic adjustment (GIA, less than 7 mm/yr in the horizontal direction and up to 33 mm/yr in the vertical direction). Velocities from the plate spreading and GIA are subtracted from the observed deformation field, to isolate the movements caused by other processes, referred to as corrected average velocity. The corrected average velocity field has horizontal movements away from the caldera and the dike in the post-eruptive period. The surface close to the caldera and near the dike uplifted. Around the caldera, the GNSS station closest to the caldera has maximum corrected uplift velocity of about 20 mm/yr and maximum corrected horizontal velocity away from the caldera of about 111 mm/yr ...
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