Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska
A surface-towed electric dipole-dipole system capable of operating in shallow water and deployable from small vessels has been developed for use in the Alaskan Arctic. Our system uses electromagnetic energy from a modulated manmade source to interrogate the underlying resistivity structure of the se...
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ftcdlib:qt30n6f618 2023-05-15T15:06:44+02:00 Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska Sherman, Joanna E 167 2018-01-01 application/pdf http://www.escholarship.org/uc/item/30n6f618 en eng eScholarship, University of California http://www.escholarship.org/uc/item/30n6f618 qt30n6f618 public Sherman, Joanna E. (2018). Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska. UC San Diego: Earth Sciences. Retrieved from: http://www.escholarship.org/uc/item/30n6f618 Geophysics controlled source electromagnetic systems gas hydrate permafrost dissertation 2018 ftcdlib 2018-03-30T22:51:23Z A surface-towed electric dipole-dipole system capable of operating in shallow water and deployable from small vessels has been developed for use in the Alaskan Arctic. Our system uses electromagnetic energy from a modulated manmade source to interrogate the underlying resistivity structure of the seafloor. We used this system in the summers of 2014 and 2015 to map subsea ice-bearing permafrost on the Beaufort Shelf along 200~km of coastline, from Tigvariak Island to Harrison Bay. Permafrost is resistive and was found to be anisotropic, likely due to interbedded layers of frozen and unfrozen sediment. Maps of depth to permafrost and its thickness were produced from electrical resistivity inversions and results compared to borehole logs in the area. We observed elevated resistivity values offshore the Sagavanirktok River outflow, supporting the idea that fresh groundwater flow has a preserving effect on submerged permafrost. This system provides a cost effective method that could be used to further quantify permafrost extent, provide a baseline for measurements of future degradation, and provide observational constraints to aid in permafrost modeling studies. Doctoral or Postdoctoral Thesis Arctic Ice permafrost Alaska University of California: eScholarship Arctic Beaufort Shelf ENVELOPE(-142.500,-142.500,70.000,70.000) |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Geophysics controlled source electromagnetic systems gas hydrate permafrost |
spellingShingle |
Geophysics controlled source electromagnetic systems gas hydrate permafrost Sherman, Joanna E Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska |
topic_facet |
Geophysics controlled source electromagnetic systems gas hydrate permafrost |
description |
A surface-towed electric dipole-dipole system capable of operating in shallow water and deployable from small vessels has been developed for use in the Alaskan Arctic. Our system uses electromagnetic energy from a modulated manmade source to interrogate the underlying resistivity structure of the seafloor. We used this system in the summers of 2014 and 2015 to map subsea ice-bearing permafrost on the Beaufort Shelf along 200~km of coastline, from Tigvariak Island to Harrison Bay. Permafrost is resistive and was found to be anisotropic, likely due to interbedded layers of frozen and unfrozen sediment. Maps of depth to permafrost and its thickness were produced from electrical resistivity inversions and results compared to borehole logs in the area. We observed elevated resistivity values offshore the Sagavanirktok River outflow, supporting the idea that fresh groundwater flow has a preserving effect on submerged permafrost. This system provides a cost effective method that could be used to further quantify permafrost extent, provide a baseline for measurements of future degradation, and provide observational constraints to aid in permafrost modeling studies. |
format |
Doctoral or Postdoctoral Thesis |
author |
Sherman, Joanna E |
author_facet |
Sherman, Joanna E |
author_sort |
Sherman, Joanna E |
title |
Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska |
title_short |
Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska |
title_full |
Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska |
title_fullStr |
Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska |
title_full_unstemmed |
Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska |
title_sort |
surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the beaufort shelf, alaska |
publisher |
eScholarship, University of California |
publishDate |
2018 |
url |
http://www.escholarship.org/uc/item/30n6f618 |
op_coverage |
167 |
long_lat |
ENVELOPE(-142.500,-142.500,70.000,70.000) |
geographic |
Arctic Beaufort Shelf |
geographic_facet |
Arctic Beaufort Shelf |
genre |
Arctic Ice permafrost Alaska |
genre_facet |
Arctic Ice permafrost Alaska |
op_source |
Sherman, Joanna E. (2018). Surface-towed controlled source electromagnetic system for mapping extent of subsea permafrost on the Beaufort shelf, Alaska. UC San Diego: Earth Sciences. Retrieved from: http://www.escholarship.org/uc/item/30n6f618 |
op_relation |
http://www.escholarship.org/uc/item/30n6f618 qt30n6f618 |
op_rights |
public |
_version_ |
1766338292164329472 |