Seismic Monitoring of Permafrost in Svalbard, Arctic Norway
| Autor: | Isabelle Lecomte, Julie Albaric, Ulrich Polom, Nadège Langet, Dave Harris, Gregor Hillers, Matthias Ohrnberger, Daniela Kühn |
|---|---|
| Přispěvatelé: | Department of Geosciences and Geography, Institute of Seismology, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Norwegian Seismic Array (NORSAR), Institut für Geowissenschaften, Universität Potsdam, Deschutes Signal Processing LLC, Maupin, Oregon, Leibniz Institute for Applied Physics, Department of Earth Science, University of Bergen, Institute of Seismology, University of Helsinki, Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC) |
| Rok vydání: | 2021 |
| Předmět: |
1171 Geosciences
010504 meteorology & atmospheric sciences [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] RESIF Ambient noise level [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Seismic noise 010502 geochemistry & geophysics Permafrost 01 natural sciences Physics::Geophysics Freezing point symbols.namesake Geophysics Arctic 13. Climate action Seismic array symbols Shear velocity Rayleigh wave [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment Geology Seismology 0105 earth and related environmental sciences |
| Zdroj: | Seismological Research Letters Seismological Research Letters, Seismological Society of America, 2021, ⟨10.1785/0220200470⟩ |
| ISSN: | 1938-2057 0895-0695 |
| DOI: | 10.1785/0220200470 |
| Popis: | We analyze data from passive and active seismic experiments conducted in the Adventdalen valley of Svalbard in the Norwegian Arctic. Our objective is to characterize the ambient wavefield of the region and to investigate permafrost dynamics through estimates of seismic velocity variations. We are motivated by a need for early geophysical detection of potentially hazardous changes to permafrost stability. We draw upon several data sources to constrain various aspects of seismic wave propagation in Adventdalen. We use f-k analysis of five years of continuous data from the Spitsbergen seismic array (SPITS) to demonstrate that ambient seismic noise on Svalbard consists of continuously present body waves and intermittent surface waves appearing at regular intervals. A change in wavefield direction accompanies the sudden onset of surface waves when the average temperature rises above the freezing point, suggesting a cryogenic origin. This hypothesis is supported further by our analysis of records from a temporary broadband network, which indicates that the background wavefield is dominated by icequakes. Synthetic Green’s functions calculated from a 3D velocity model match well with empirical Green’s functions constructed from the recorded ambient seismic noise. We use a shallow shear-wave velocity model, obtained from active seismic measurements, to estimate the maximum depth of Rayleigh wave sensitivity to changes in shear velocity to be in the 50–100 m range. We extract seasonal variations in seismic velocities from ambient noise cross-correlation functions computed over three years of SPITS data. We attribute relative velocity variations to changes in the ice content of the shallow (2–4 m depth) permafrost, which is sensitive to seasonal temperature changes. A linear decreasing trend in seismic velocity is observed over the years, most likely due to permafrost warming. |
| Databáze: | OpenAIRE |
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