| Summary: | The Holuhraun eruption of 2014-2015 was the largest volcanic eruption in Iceland in 230 years. During the eruption, the subglacial Bárðarbunga caldera collapsed, caused by the emptying of its magma chamber. The resultant deformation was mon- itored through a variety of geophysical techniques, revealing a ∼ 62 m deep surface depression in the ice. Such collapses are rare and seldom recorded instrumentally. However, the direct measurement of subglacial crustal deformation is challenging as it is largely obscured by overlying ice motion. To investigate post-eruptive behaviour in the period 2017-2022, interferometry and field techniques are used to calculate the ice-volume balance of the caldera. The line-of-sight signal derived from one-day interferograms is resolved into the horizontal ice surface velocity. The ice volume leaving the caldera is calculated using a series of flux gates. The volume budget of the study area indicates an overall ice volume loss of -0.35 ± 0.11 km3 unattributed to flux out of the caldera, changes in surface elevation or surface mass balance. Since previous studies have identified signs of uplift in the caldera floor, this unaccounted for volume is attributed to significant melting at the bed, requiring approximately 680 ±220 MW of power is required to sustain sufficient melting. Of this, 210 ±100 MW is attributed to the cauldron on the south-eastern rim, BB-03. These derived powers represent an underestimate of the geothermal power at the bed and these results do not exclude the potential for uplift of the caldera floor. A further 80 MW would be required for 1m of uplift over the five year period. These results and other observations are considered in relation to previous estimates of Bárðarbunga’s geothermal power. Gosið í Holuhrauni var það stærsta á Íslandi í 230 ár. Á meðan gosinu stóð seig gólf Bárðarbunguöskjunnar, vegna tæmingar kvikuhólfsins þar undir. Við lok gossins hafði myndast 62 m djúp lægð í jökulyfirborðið af þeim sökum. Slík öskjusig eru sjaldgæf og fá dæmi um að ...
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