| Title | The Interaction of the Plate Boundary Movement in 2020 and Exploitation of Geothermal Fields on the Reykjanes Peninsula, Iceland |
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| Authors | Ólafur G. FLÓVENZ. Vincent DROUIN, Kristján ÃGÚSTSSON, Egill Ãrni GUÃNASON, Gylfi Páll HERSIR. Thorbjörg ÃGÚSTSDÓTTIR, Ingvar Þór MAGNÚSSON, Claus MILKEREIT, Torsten DAHM and Philippe JOUSSET |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Reykjanes peninsula, uplift, reinjection, magma intrusion, earthquakes, brittle ductile boundary |
| Abstract | January 22nd, 2020 an intense earthquake swarm started just east of the Svartsengi geothermal field on the Reykjanes Peninsula in SW-Iceland. Simultaneously, a rapid uplift started in the middle of the geothermal field centred close to the re-injection wells of the Svartsengi power plant. The seismic activity was strongly episodic, and during the following months it spread over a large proportion of the plate boundary along the Reykjanes Peninsula. There are indications that the original seismicity might have been triggered by the pressure increase at the source of uplift underneath the geothermal field. The vertical displacement consisted of three periods of uplift from January to July separated by periods of subsidence. Since Mid-July 2020, continuous subsidence has been ongoing. The character of the seismic activity is typical for the classical plate movements along the plate boundary of the peninsula, where oblique rift prevails while the cause of the uplift is debated. Possible explanations are three magmatic intrusions forming narrow and thin sills at shallow depth below the geothermal field, fluid expansion and contraction phenomena beneath the re-injection wells or a mixture of both effects. An intrusion of mantle CO2 is also a candidate. Our evaluation of the available data does not prove or disprove any of the hypotheses on the origin of the pressure and volume increase at the source of the uplift. In future modelling we consider important to account for the high temperature, pressure, and permeability at the source of uplift and possible interaction between magma, carbon dioxide and the in-situ geothermal fluid. |