Continuous Microgravity Monitoring in a Volcanic Geothermal Field: Integrated Observational Approach in Þeistareykir, NE Iceland.

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Continuous Microgravity Monitoring in a Volcanic Geothermal Field: Integrated Observational Approach in Þeistareykir, NE Iceland.

Journal Article (2021)

Author(s)

Kemal Erbas (GFZ Helmholtz-Zentrum für Geoforschung)

Florian Schäfer (GFZ Helmholtz-Zentrum für Geoforschung)

Ásgrímur Guðmundson2 (Landsvirkjun, National Power Company of Iceland)

Egill Júlíusson (Landsvirkjun, National Power Company of Iceland)

Gylfi Páll Hersir (Iceland GeoSurvey (ISOR))

Richard J. Warburton ( GWR Instruments, Inc.)

Jean-Daniel Bernard (EOST)

Nolwenn Portier (EOST)

Jacques Hinderer (EOST)

Vincent Drouin (University of Iceland)

Freysteinn Sigmundsson (University of Iceland)

Kristján Ágústsson3 (Iceland GeoSurvey (ISOR))

Benjamin Männel (GFZ Helmholtz-Zentrum für Geoforschung)

Andreas Güntner (GFZ Helmholtz-Zentrum für Geoforschung)

Christian Voigt (GFZ Helmholtz-Zentrum für Geoforschung)

Tilo Schöne (GFZ Helmholtz-Zentrum für Geoforschung)

Arthur Jolly (GNS Science)

Hreinn Hjartasson (Landsvirkjun, National Power Company of Iceland)

D.F. Naranjo Hernandez (GFZ Helmholtz-Zentrum für Geoforschung, ETH Zürich)

Philippe Jousset (GFZ Helmholtz-Zentrum für Geoforschung)

URL related publication

https://pangea.stanford.edu/ERE/db/WGC/papers/WGC/2020/13124.pdf Final published version

To reference this document use

https://resolver.tudelft.nl/uuid:61b26e4b-7f44-493c-ba8b-b4282568b737

More Info

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Publication Year

2021

Language

English

Journal title

Proceedings World Geothermal Congress 2020. Reykjavik, Iceland, April-October 2021

Article number

paper 13124

Downloads counter

318

Abstract

In volcanic and hydrothermal geosystems, monitoring of mass and stress changes provide information for both volcanic hazardassessment and estimation of geothermal resources. The combined continuous recording of the gravity field and ground motionwith sufficient accuracy in an active volcano-tectonic setting allows a better understanding of the mass and stress transfermechanisms that produce short term gravity changes and local seismic activity. The aim is to gain a better understanding ofgeothermal system processes by addressing short-term mass changes within geothermal reservoirs in relation to external influencessuch as anthropogenic (reservoir exploitation) and natural forcing (local and regional earthquake activity and earth tides). Thiscontributes to knowing the reservoir properties, structure and long-term behaviour.Þheistareykir (Northeast Iceland), where the geothermal power production started in autumn 2017 (2x45 MWe) is the site chosenfor this unique experiment. The overall goal of the project is to use a network of continuously measuring gravity meters to detectsmall variations in gravity associated with managing a geothermal field (injection and extraction). The gravity changes are expectedto be small: ~5 µgal/6 months (1 µgal=10-8 ms-2). Therefore, high performance and up-to-date instrumentation such assuperconducting gravity meters (SG), spring gravity meters and broadband seismometers are used. To achieve these goals, inautumn 2017 a network of 5 relative gravity meters (3 iGravs and 2 gPhones) and 14 seismic stations were deployed. Three gravitymonitoring sites are in close vicinity to the production and injection area, and one iGrav is set up outside the geothermal field forreference. Presented in this report are the details of the infrastructure and instruments deployed and the first results of more than 18months of continuous gravity and seismicity monitoring.