Using array‐derived rotational motion to obtain local wave propagation properties from earthquakes induced by the 2018 geothermal stimulation in Finland

Tutkimustuotos: ArtikkelijulkaisuArtikkeliTieteellinenvertaisarvioitu

Abstrakti

We estimate vertical rotation rates for 204 earthquakes that were induced by the 2018 stimulation of the Espoo/Helsinki geothermal reservoir from wavefield gradients across geophone arrays. The array-derived rotation rates from seismograms recorded at 6-9 km hypocentral distances vary between 10(-9) and 10(-7) rad s(-1), indicating a comparable sensitivity to portable rotational instruments. Using co-located observations of translational and rotational motion, we estimate the local propagation direction and the apparent phase speed of SH waves, and compare these estimates with those obtained by S wave beamforming. Propagation directions generally align with the earthquake back azimuths, but both techniques show deviations indicative of heterogeneous seismic structure. The rotational method facilitates a station-by-station approach that resolves site specific variations that are controlled by the local geology. We measure apparent S wave speeds larger than 5 km s(-1), consistent with steep incidence angles and high propagation velocities in the Fennoscandian Shield.

Alkuperäiskielienglanti
ArtikkeliARTN e2020GL090403
LehtiGeophysical Research Letters
Vuosikerta48
Numero6
Sivumäärä11
ISSN0094-8276
DOI - pysyväislinkit
TilaJulkaistu - 28 maaliskuuta 2021
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä, vertaisarvioitu

Tieteenalat

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