Detection of Subsea Permafrost Using Shallow Georesistivity at Three Arctic Sites


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Paul.Overduin [ at ] awi.de

Abstract

This study focuses on a coupled understanding of coastal erosion and submarine permafrost dynamics at 3 arctic sites, where long-term observations of coastal change, historical subsea permafrost core data from the 1980s and recently obtained geophysical data of subsea permafrost are available. In this context, observations of changes in coastal geomorphology are coupled with geophysical observations along a historic submarine sub-bottom profiles. The rate of permafrost degradation in the littoral zone is controlled by a number of factors. The sea bottom water temperature and salinity control warming and salt penetration into the sediment column. Sediment deposition, re-suspension and transport by wave action and entrainment in ice are important in determining initial rates of degradation in the water depths where wave cycles reach the sea bed. Where the water depth is less than the sea ice thickness, bottom-fast ice (BFI) forms and affects the sea bed. The duration of inundation controls the length of time over which these factors influence the sea bed and increases with seaward distance from the coastline. Thus, the rate of coastal retreat affects the inclination of the IBPF table within the sediment. If erosion is rapid, and permafrost degradation rates in the littoral zone are negligible, the permafrost table lies close to the sea bed (upper figure A). If other factors are similar, a low coastal retreat rate leads to a steeper inclination of the IBPF table (middle figure B). Observations show inclinations between 0.14 and 2° below horizontal [Overduin et al., 2007] that vary between and within sites, suggesting that the relative importance of factors affecting IBPF table inclination varies spatially between sites and over time at each site (e.g. lower figure C). Here we present observations of the geoelectrical resistivity of the seabed, and compare interpreted IBPF positions from this observations with observations from the literature. We include near shore (< 10 m water depth) IBPF table inclinations determined by probing, drilling and temperature and their dependence on coastline position change rates.



Item Type
Conference (Poster)
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
Annual Meeting. Permafrost Working Group, German Polar Society, 15 Nov 2012 - 17 Nov 2012, Potsdam, Germany.
Eprint ID
32160
Cite as
Overduin, P. , Wetterich, S. , Makarov, A. S. and Grigoriev, M. N. (2012): Detection of Subsea Permafrost Using Shallow Georesistivity at Three Arctic Sites , Annual Meeting. Permafrost Working Group, German Polar Society, Potsdam, Germany, 15 November 2012 - 17 November 2012 .


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