Monitoring an Enhanced Geothermal System in Downtown Helsinki

Kuvaus

In June and July 2018 St1 Deep Heat Oy (ST1DH) performed hydraulic stimulation between 6
km and 7 km depth beneath the Aalto University campus, in Otaniemi, Espoo, Finland, to
establish an Enhanced Geothermal System (EGS) doublet for district heating. The
remarkable depth of the stimulation can be attributed to the shallow geothermal gradient
intrinsic to the geologically stable Fennoscandian shield. The Institute of Seismology,
University of Helsinki (ISUH) monitored the stimulation stage using a network of surface
seismic stations and geophones.
The EGS-site is located near the center of Greater Helsinki in Southern Finland; a region that
has low natural seismicity and shallow to non-existent sedimentary cover. Many sensitive
installations and other infrastructure are situated within few kilometers of the site. These
provide unique challenges, requirements but also opportunities for the seismic monitoring of
the project.
We present the various seismic networks that were used in monitoring the site, as well as the
induced seismicity that was observed during and after the stimulation. We will also briefly
discuss the public response to the induced seismicity with focus on the largest event. For
background, the natural seismicity of Southern Finland is briefly covered, as well as the so called Traffic Light System (TLS) that was used during the stimulation to manage the induced
seismicity

Aikajakso	15 lokakuuta 2019
Tapahtuman otsikko	The 50th Nordic Seminar in Seismology
Tapahtuman tyyppi	Seminaari
Sijainti	Uppsala, Ruotsi
Tunnustuksen arvo	Kansainvälinen