EGU22-531, updated on 26 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Temporal deformation in the Hellisheiði geothermal field and its adjacent Húsmúli injection field explained by poroelastic modelling

Cécile Ducrocq1, Elías Rafn Heimisson2, Halldór Geirsson1, Thóra Árnadóttir1, Gudni Axelsson3, Vala Hjörleifsdóttir4, and Vincent Drouin5
Cécile Ducrocq et al.
  • 1Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland (
  • 2Swiss Seismological Service, ETH Zurich, Zurich, Switzerland
  • 3GRÓ Geothermal Training Programme, Reykjavík, Iceland
  • 4Reykjavik Energy, Reykjavík, Iceland
  • 5Icelandic Meteorological Office, Reykjavík, Iceland

Crustal deformation allows us to monitor and understand critical properties of exploited geothermal systems around the world. The Hellisheiði high-temperature geothermal field (in 2011: 303MWe and 133MWth) in SW Iceland has been previously studied using Global Navigation Satellite Systems (GNSS) and Interferometry Synthetic Aperture Radar (InSAR) data between 2011 and 2015. These studies characterized the subsidence rate related to the extraction of fluids in the Hellisheiði area, as well as a 4-month uplift at the start of injection of geothermal fluids in the Húsmúli area. This uplift was accompanied by significant seismicity culminating with two ML >3.5 earthquakes felt in the surrounding region.

We carry out further analysis of GNSS and InSAR data between 2011 and 2019 that show a total of three uplift events, separated by periods of subsidence or little deformation in the Húsmúli area. The deformation episodes seem to correlate with heightened seismic activity despite the continued decrease of injected mass flow rate in the original injection boreholes.

Here we use a finite element poroelastic model (COMSOL Multiphysics) to relate the extraction and injection of the adjacent Hellisheiði and Húsmúli areas to the ground deformation within the same time span. We assume that the boreholes can be represented by three point-injector sources: one of negative mass flow rate in Hellisheiði, and two of positive mass flow rates in (west and east) Húsmúli. The three sources are necessary to explain the deformation observed between 2011 and 2019. The poroelastic model presents insights into the temporal response of geothermal systems from extraction/injection, changes in exploitations and variability in permeability all of which induce heightened strain and stress in the fractured Húsmúli region. We investigate if poroelastic effects may be responsible for triggering transient earthquake swarms and to what degree poroelasiticy can explain the spatially and temporally complex uplift and subsidence. We suggest this study offers new insights into the Hellisheiði geothermal system that are transferable to geothermal systems around the world.

How to cite: Ducrocq, C., Heimisson, E. R., Geirsson, H., Árnadóttir, T., Axelsson, G., Hjörleifsdóttir, V., and Drouin, V.: Temporal deformation in the Hellisheiði geothermal field and its adjacent Húsmúli injection field explained by poroelastic modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-531,, 2022.