Tammervoiman geotermisen voimalan seisminen monitorointi 2021

In summer 2021 Tampereen Sähkölaitos and Tammervoma started drilling a deep geothermal well as a pilot project on the Tarastenjärvi power plant premises in Tampere. In addition to local companies the Kaupunkilämpö consortium of 15 urban energy companies from Finland is involved in the project. Main operator is Thermo Rock Oy. In the first phase of the project, the goal is to reach three kilometers depth.

For seismic monitoring of the project Institute of Seismology University of Helsinki istalled a network consisting of one real-time broad-band seismic station and six geophone stations. Real-time seismic monitoring of Tarastenjärvi area was incorporated into the institute's national seismic monitoring. A procedure for fast communication to the operators and authorities monitoring the project was established in case of observed earthquakes.

Within 20 kilometers from the Tarastenjärvi power plant 90 seismic events were detected and localized from the year 2021 seismic data. All were explosions from quarries or construction sites. Fifty events were detected and analysed as a part of national seismic monitoring. Magnitudes of those events were between 0.1 and 1.3 with a median of 0.7. During the project's monitoring period from May 18th to November 31st forty additional small events were detected and later analysed with data from the geophone network. Magnitudes of these events were between -0.7 and 1.3 with a median of 0.1. An automatic detector applied to geophone data revealed even more small events but no earthquakes, and none of the events were in the immediate proximity of the Tarastenjärvi power plant.