Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography
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 b...
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ftcopernicus:oai:publications.copernicus.org:egusphere119291 2024-06-23T07:50:53+00:00 Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography Erkens, Ephraim Angelopoulos, Michael Tronicke, Jens Dallimore, Scott R. Whalen, Dustin Boike, Julia Overduin, Pier Paul 2024-04-12 application/pdf https://doi.org/10.5194/egusphere-2024-1044 https://egusphere.copernicus.org/preprints/2024/egusphere-2024-1044/ eng eng doi:10.5194/egusphere-2024-1044 https://egusphere.copernicus.org/preprints/2024/egusphere-2024-1044/ eISSN: Text 2024 ftcopernicus https://doi.org/10.5194/egusphere-2024-1044 2024-06-13T01:25:01Z 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. Text Arctic Beaufort Sea Ice permafrost Copernicus Publications: E-Journals Arctic Canada Tuktoyaktuk ENVELOPE(-133.006,-133.006,69.425,69.425) Tuktoyaktuk Island ENVELOPE(-133.009,-133.009,69.454,69.454) |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
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. |
format |
Text |
author |
Erkens, Ephraim Angelopoulos, Michael Tronicke, Jens Dallimore, Scott R. Whalen, Dustin Boike, Julia Overduin, Pier Paul |
spellingShingle |
Erkens, Ephraim Angelopoulos, Michael Tronicke, Jens Dallimore, Scott R. Whalen, Dustin Boike, Julia Overduin, Pier Paul Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography |
author_facet |
Erkens, Ephraim Angelopoulos, Michael Tronicke, Jens Dallimore, Scott R. Whalen, Dustin Boike, Julia Overduin, Pier Paul |
author_sort |
Erkens, Ephraim |
title |
Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography |
title_short |
Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography |
title_full |
Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography |
title_fullStr |
Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography |
title_full_unstemmed |
Mapping subsea permafrost around Tuktoyaktuk Island (NWT, Canada) using electrical resistivity tomography |
title_sort |
mapping subsea permafrost around tuktoyaktuk island (nwt, canada) using electrical resistivity tomography |
publishDate |
2024 |
url |
https://doi.org/10.5194/egusphere-2024-1044 https://egusphere.copernicus.org/preprints/2024/egusphere-2024-1044/ |
long_lat |
ENVELOPE(-133.006,-133.006,69.425,69.425) ENVELOPE(-133.009,-133.009,69.454,69.454) |
geographic |
Arctic Canada Tuktoyaktuk Tuktoyaktuk Island |
geographic_facet |
Arctic Canada Tuktoyaktuk Tuktoyaktuk Island |
genre |
Arctic Beaufort Sea Ice permafrost |
genre_facet |
Arctic Beaufort Sea Ice permafrost |
op_source |
eISSN: |
op_relation |
doi:10.5194/egusphere-2024-1044 https://egusphere.copernicus.org/preprints/2024/egusphere-2024-1044/ |
op_doi |
https://doi.org/10.5194/egusphere-2024-1044 |
_version_ |
1802641821750263808 |