Ground Deformation After a Caldera Collapse: Contributions of Magma Inflow and Viscoelastic Response to the 2015–2018 Deformation Field Around Bárðarbunga, Iceland

Abstract

Ground deformation indicating volcano inflation, increase in seismic activity, changes in volcanic gas release, and thermal anomalies within a volcanic system are generally recognized as the indicators of volcanic unrest (e.g.,

Post‐Rifting Relaxation During 2015–2020 Following the Bárðarbunga‐Holuhraun Dike Intrusion and Eruption in Iceland

“…We use the semi-analytical software RELAX (Barbot & Fialko, 2010a, 2010b to calculate post-rifting displacement fields in response to the formation of a dike. We start with a two-layer Maxwell viscoelastic model, where a 7 km thick elastic layer lies on top of a 0.3 × 10 19 Pa s viscoelastic half-space, as described by Li et al (2021). Both layers consist of homogeneous isotropic material, with Poisson's ratio ν = 0.25 and shear modulus μ = 16 GPa (Grapenthin et al, 2006).…”

“…We explore elastic layer thickness ranging from 1 to 24 km in steps of 1 km. As the displacement rate predicted by the viscoelastic model scales inversely with viscosity, we derive the result of different viscosities by scaling the displacement rate of the initial model, as done by Li et al (2021). We test viscosities in 0.1 × 10 19 Pa s steps from 0.3-3.6 × 10 19 Pa s.…”

“…Li et al (2021) applied a scaling factor to the GIA model from Auriac (2014) to correct for the GIA displacement during the period 2015-2018. We assume the GIA signal does not change from 2015 to 2020 and apply the same scaling factor to correct for the GIA signal as done by Li et al (2021). Plate spreading in our study area is caused by the divergent plate movements as the Eurasian and North American plates move apart.…”

“…We assume the GIA signal does not change from 2015 to 2020 and apply the same scaling factor to correct for the GIA signal as done by Li et al. (2021). Plate spreading in our study area is caused by the divergent plate movements as the Eurasian and North American plates move apart.…”

“…GIA generates surface uplift and displacement toward the north, as suggested by the model from Auriac (2014). Li et al (2021) applied a scaling factor to the GIA model from Auriac (2014) to correct for the GIA displacement during the period 2015-2018. We assume the GIA signal does not change from 2015 to 2020 and apply the same scaling factor to correct for the GIA signal as done by Li et al (2021).…”