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Preprints
https://doi.org/10.5194/egusphere-2024-1044
https://doi.org/10.5194/egusphere-2024-1044
12 Apr 2024
 | 12 Apr 2024

Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography

Ephraim Erkens, Michael Angelopoulos, Jens Tronicke, Scott R. Dallimore, Dustin Whalen, Julia Boike, and Pier Paul Overduin

Abstract. Along much of the Arctic coast, shoreline retreat and sea level rise combine to inundate permafrost. Once inundated by seawater permafrost usually begins to degrade. Tuktoyaktuk Island (Beaufort Sea, NWT, Canada) is an important natural barrier protecting the harbor of Tuktoyaktuk, but will likely be breached within the next three decades. The state of subsea permafrost and its depth distribution around the island are, however, still largely unknown. We collected marine electrical resistivity tomography (ERT) surveys (vertical electrical soundings) north and south of Tuktoyaktuk Island using a floating cable with 13 electrodes in a quasi-symmetric Wenner-Schlumberger array. We filtered the data with a new approach to eliminate potentially falsified measurements due to a curved cable and inverted the profiles with a variety of parameterizations to estimate the position of the top of the ice-bearing permafrost table (IBPT) below the sea floor. Our results indicate that north of Tuktoyaktuk Island, where coastal erosion is considerably faster, IBPT depths range from 5 m below sea level (120 m from the shoreline) to around 20 m bsl (up to 800 m from the shoreline). South of the island, the IBPT dips more steeply and lies at 10 m bsl a few meters from the shore to more than 30 m bsl 200 m from the shore. We discuss how marine ERT measurements can be improved by recording electrode position, but choices made in data inversion can be a more likely source of uncertainty in IBPT position than electrode positions. At Tuktoyaktuk Island, IBPT depths below the sea floor increase with distance from the shoreline; comparing the northern and southern sides of the island, its inclination is inversely proportional to coastline retreat rates. On the island’s north side, historical coastal retreat rate suggests a mean degradation rate of 5.3 ± 4.0 cm/yr.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint

06 Mar 2025
Mapping subsea permafrost around Tuktoyaktuk Island (Northwest Territories, Canada) using electrical resistivity tomography
Ephraim Erkens, Michael Angelopoulos, Jens Tronicke, Scott R. Dallimore, Dustin Whalen, Julia Boike, and Pier Paul Overduin
The Cryosphere, 19, 997–1012, https://doi.org/10.5194/tc-19-997-2025,https://doi.org/10.5194/tc-19-997-2025, 2025
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

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We investigate the depth of subsea permafrost formed by inundation of terrestrial permafrost due...
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