Seismic Monitoring of Permafrost in Svalbard, Arctic Norway

• Published in: Seismological Research Letters
• Main Authors: Albaric, Julie, Kühn, Daniela, Ohrnberger, Matthias, Langet, Nadège, Harris, Dave, Polom, Ulrich, Lecomte, Isabelle, Hillers, Gregor
• Other Authors: Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté COMUE (UBFC)-Université Bourgogne Franche-Comté COMUE (UBFC), Norwegian Seismic Array (NORSAR), Institut für Geowissenschaften, University of Potsdam = Universität Potsdam, Deschutes Signal Processing LLC, Maupin, Oregon, Leibniz Institute for Applied Physics, Leibniz Association, University of Bergen (UiB), Helsingin yliopisto = Helsingfors universitet = University of Helsinki
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: RESIF; Epos-France; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Adventdalen; Arctic; Ice; permafrost; Svalbard; Spitsbergen
• Online Access: https://hal.science/hal-03286889; https://doi.org/10.1785/0220200470

Dans le cadre de l’intégration aux dispositions européens EPOS, Résif s'est transformé en octobre 2023 en Epos-France, une nouvelle infrastructure de recherche aux contours thématiques plus larges et en accord avec ceux de sa grande sœur européenne. International audience Abstract 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 ...