Post-Rifting Relaxation During 2015-2020 Following the Baroarbunga-Holuhraun Dike Intrusion and Eruption in Iceland

Post-rifting ground deformation may be driven by viscoelastic relaxation of stresses generated by dike intrusions. The single-dike intrusion of the 2014-2015 Baroarbunga eruption in Iceland presents an opportunity for a detailed study of this process. We use continuous Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) velocity fields to analyze the 2015-2020 post-rifting deformation, showing uplift on both sides of the dike and horizontal displacement away from the dike after correcting for background deformation. Two GNSS stations experience baseline lengthening at a rate of 19 mm/yr in the direction perpendicular to the strike of the dike. A two-layer viscoelastic model with a 0.4 x 10(19) Pa s viscoelastic half-space overlain by an 18 km thick elastic layer best explains the observed horizontal and vertical InSAR and GNSS displacements. The model misfit space shows a second regime of good fit, likely driven by deformation near the dike that may result from cooling compaction of the emplaced dike.

Automated summary

Post-rifting ground deformation is driven by the relaxation of stresses generated by dike intrusions. Using GNSS and InSAR velocity fields, we analyzed the post-rifting deformation from 2015 to 2020 in the Baroarbunga eruption in Iceland. The results showed uplift on both sides of the dike and horizontal displacement away from the dike after accounting for background deformation. A two-layer viscoelastic model with a 0.4 x 10(19) Pa s viscoelastic half-space and an 18 km thick elastic layer best explained the observed displacements. The model also highlighted another regime of good fit, possibly due to deformation near the dike caused by cooling compaction.