The 2018 Geothermal Reservoir Stimulation in Espoo/Helsinki, Southern Finland: Seismic Network Anatomy and Data Features

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dc.contributor.author Hillers, Gregor
dc.contributor.author Vuorinen, Tommi A.T.
dc.contributor.author Uski, Marja
dc.contributor.author Kortström, Jari
dc.contributor.author Mäntyniemi, Päivi
dc.contributor.author Tiira, Timo
dc.contributor.author Malin, Peter E.
dc.contributor.author Saarno, Tero
dc.date.accessioned 2021-02-09T10:43:01Z
dc.date.available 2021-02-09T10:43:01Z
dc.date.issued 2020-03
dc.identifier.citation Hillers , G , Vuorinen , T A T , Uski , M , Kortström , J , Mäntyniemi , P , Tiira , T , Malin , P E & Saarno , T 2020 , ' The 2018 Geothermal Reservoir Stimulation in Espoo/Helsinki, Southern Finland: Seismic Network Anatomy and Data Features ' , Seismological Research Letters , vol. 91 , no. 2 , pp. 770-786 . https://doi.org/10.1785/0220190253
dc.identifier.other PURE: 131540197
dc.identifier.other PURE UUID: c921f1d1-aef4-486f-a54b-ee7ecea76386
dc.identifier.other WOS: 000518383600022
dc.identifier.other ORCID: /0000-0002-7617-8150/work/71512158
dc.identifier.other ORCID: /0000-0001-9447-6146/work/71512197
dc.identifier.other ORCID: /0000-0001-9211-8273/work/71512285
dc.identifier.other ORCID: /0000-0002-8186-012X/work/71512567
dc.identifier.other ORCID: /0000-0003-2341-1892/work/71513365
dc.identifier.uri http://hdl.handle.net/10138/326211
dc.description.abstract A seismic network was installed in Helsinki, Finland to monitor the response to an similar to 6-kilometer-deep geothermal stimulation experiment in 2018. We present initial results of multiple induced earthquake seismogram and ambient wavefield analyses. The used data are from parts of the borehole network deployed by the operating St1 Deep Heat Company, from surface broadband sensors and 100 geophones installed by the Institute of Seismology, University of Helsinki, and from Finnish National Seismic Network stations. Records collected in the urban environment contain many signals associated with anthropogenic activity. This results in time- and frequency-dependent variations of the signal-to-noise ratio of earthquake records from a 260-meter-deep borehole sensor compared to the combined signals of 24 collocated surface array sensors. Manual relocations of similar to 500 events indicate three distinct zones of induced earthquake activity that are consistent with the three clusters of seismicity identified by the company. The fault-plane solutions of 14 selected ML 0.6-1.8 events indicate a dominant reverse-faulting style, and the associated SH radiation patterns appear to control the first-order features of the macroseismic report distribution. Beamforming of earthquake data from six arrays suggests heterogeneous medium properties, in particular between the injection site and two arrays to the west and southwest. Ambient-noise cross-correlation functions reconstruct regional surface-wave propagation and path-dependent body-wave propagation. A 1D inversion of the weakly dispersive surface waves reveals average shear-wave velocities around 3.3 km/s below 20 m depth. Consistent features observed in relative velocity change time series and in temporal variations of a proxy for wavefield partitioning likely reflect the medium response to the stimulation. The resolution properties of the obtained data can inform future monitoring strategies and network designs around natural laboratories. en
dc.format.extent 17
dc.language.iso eng
dc.relation.ispartof Seismological Research Letters
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject 1171 Geosciences
dc.subject FLUID-INJECTION
dc.subject EARTHQUAKES
dc.subject SENSITIVITY
dc.subject SYSTEM
dc.subject DEPTH
dc.subject SCALE
dc.subject ARRAY
dc.subject SITE
dc.title The 2018 Geothermal Reservoir Stimulation in Espoo/Helsinki, Southern Finland: Seismic Network Anatomy and Data Features en
dc.type Article
dc.contributor.organization Department of Geosciences and Geography
dc.contributor.organization Institute of Seismology
dc.description.reviewstatus Peer reviewed
dc.relation.doi https://doi.org/10.1785/0220190253
dc.relation.issn 0895-0695
dc.rights.accesslevel openAccess
dc.type.version acceptedVersion

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