Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand
Icy debris fans have recently been described as fan shaped depositional landforms associated with (or formed during) deglaciation, however, the subsurface characteristics remain essentially undocumented. We used ground penetrating radar (GPR) to non-invasively investigate the subsurface characterist...
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ftbucknelluniv:oai:digitalcommons.bucknell.edu:fac_journ-2532 2023-05-15T16:20:20+02:00 Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand Jacob, Robert W. Trop, Jeffrey M. Kochel, R. Craig 2018-12-01T08:00:00Z application/pdf https://digitalcommons.bucknell.edu/fac_journ/1475 https://digitalcommons.bucknell.edu/cgi/viewcontent.cgi?article=2532&context=fac_journ unknown Bucknell Digital Commons https://digitalcommons.bucknell.edu/fac_journ/1475 https://digitalcommons.bucknell.edu/cgi/viewcontent.cgi?article=2532&context=fac_journ Faculty Journal Articles ground penetrating radar GPR Alaska New Zealand Icy Debris Fans glacier McCarthy Glacier La Perouse Glacier common mid-point CMP velocity ice Geology Geomorphology Geophysics and Seismology text 2018 ftbucknelluniv 2022-04-10T18:09:44Z Icy debris fans have recently been described as fan shaped depositional landforms associated with (or formed during) deglaciation, however, the subsurface characteristics remain essentially undocumented. We used ground penetrating radar (GPR) to non-invasively investigate the subsurface characteristics of icy debris fans (IDFs) at McCarthy Glacier, Alaska, USA and at La Perouse Glacier, South Island of New Zealand. IDFs are largely unexplored paraglacial landforms in deglaciating alpine regions at the mouths of bedrock catchments between valley glaciers and icecaps. IDFs receive deposits of mainly ice and minor lithic material through different mass-flow processes, chiefly ice avalanche and to a lesser extent debris flow, slushflow, and rockfall. We report here on the GPR signal velocity observed from 15 different wide-angle reflection/refraction (WARR) soundings on the IDFs and on the McCarthy Glacier; the effect of GPR antenna orientation relative to subsurface reflections; the effect of spreading direction of the WARR soundings relative to topographic contour; observed differences between transverse electric (TE) and transverse magnetic (TM) antenna polarization; and a GPR profile extending from the McCarthy Glacier onto an IDF. Evaluation of the WARR soundings indicates that the IDF deposits have a GPR signal velocity that is similar to the underlying glacier, and that the antenna polarization and orientation did not prevent identification of GPR reflections. The GPR profile on the McCarthy Glacier indicates that the shallowest material is layered, decreases in thickness down fan, and has evidence of brittle failure planes (crevasses). The GPR profile and WARR soundings collected in 2013 indicate that the thickness of the McCarthy Glacier is 82 m in the approximate middle of the cirque and that the IDF deposits transition with depth into flowing glacial ice. Text glacier glaciers Alaska Bucknell University: Bucknell Digital Commons McCarthy ENVELOPE(66.543,66.543,-70.404,-70.404) McCarthy Glacier ENVELOPE(-127.400,-127.400,-86.067,-86.067) New Zealand |
institution |
Open Polar |
collection |
Bucknell University: Bucknell Digital Commons |
op_collection_id |
ftbucknelluniv |
language |
unknown |
topic |
ground penetrating radar GPR Alaska New Zealand Icy Debris Fans glacier McCarthy Glacier La Perouse Glacier common mid-point CMP velocity ice Geology Geomorphology Geophysics and Seismology |
spellingShingle |
ground penetrating radar GPR Alaska New Zealand Icy Debris Fans glacier McCarthy Glacier La Perouse Glacier common mid-point CMP velocity ice Geology Geomorphology Geophysics and Seismology Jacob, Robert W. Trop, Jeffrey M. Kochel, R. Craig Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand |
topic_facet |
ground penetrating radar GPR Alaska New Zealand Icy Debris Fans glacier McCarthy Glacier La Perouse Glacier common mid-point CMP velocity ice Geology Geomorphology Geophysics and Seismology |
description |
Icy debris fans have recently been described as fan shaped depositional landforms associated with (or formed during) deglaciation, however, the subsurface characteristics remain essentially undocumented. We used ground penetrating radar (GPR) to non-invasively investigate the subsurface characteristics of icy debris fans (IDFs) at McCarthy Glacier, Alaska, USA and at La Perouse Glacier, South Island of New Zealand. IDFs are largely unexplored paraglacial landforms in deglaciating alpine regions at the mouths of bedrock catchments between valley glaciers and icecaps. IDFs receive deposits of mainly ice and minor lithic material through different mass-flow processes, chiefly ice avalanche and to a lesser extent debris flow, slushflow, and rockfall. We report here on the GPR signal velocity observed from 15 different wide-angle reflection/refraction (WARR) soundings on the IDFs and on the McCarthy Glacier; the effect of GPR antenna orientation relative to subsurface reflections; the effect of spreading direction of the WARR soundings relative to topographic contour; observed differences between transverse electric (TE) and transverse magnetic (TM) antenna polarization; and a GPR profile extending from the McCarthy Glacier onto an IDF. Evaluation of the WARR soundings indicates that the IDF deposits have a GPR signal velocity that is similar to the underlying glacier, and that the antenna polarization and orientation did not prevent identification of GPR reflections. The GPR profile on the McCarthy Glacier indicates that the shallowest material is layered, decreases in thickness down fan, and has evidence of brittle failure planes (crevasses). The GPR profile and WARR soundings collected in 2013 indicate that the thickness of the McCarthy Glacier is 82 m in the approximate middle of the cirque and that the IDF deposits transition with depth into flowing glacial ice. |
format |
Text |
author |
Jacob, Robert W. Trop, Jeffrey M. Kochel, R. Craig |
author_facet |
Jacob, Robert W. Trop, Jeffrey M. Kochel, R. Craig |
author_sort |
Jacob, Robert W. |
title |
Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand |
title_short |
Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand |
title_full |
Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand |
title_fullStr |
Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand |
title_full_unstemmed |
Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand |
title_sort |
assessing ground penetrating radar's ability to image subsurface characteristics of icy debris fans in alaska and new zealand |
publisher |
Bucknell Digital Commons |
publishDate |
2018 |
url |
https://digitalcommons.bucknell.edu/fac_journ/1475 https://digitalcommons.bucknell.edu/cgi/viewcontent.cgi?article=2532&context=fac_journ |
long_lat |
ENVELOPE(66.543,66.543,-70.404,-70.404) ENVELOPE(-127.400,-127.400,-86.067,-86.067) |
geographic |
McCarthy McCarthy Glacier New Zealand |
geographic_facet |
McCarthy McCarthy Glacier New Zealand |
genre |
glacier glaciers Alaska |
genre_facet |
glacier glaciers Alaska |
op_source |
Faculty Journal Articles |
op_relation |
https://digitalcommons.bucknell.edu/fac_journ/1475 https://digitalcommons.bucknell.edu/cgi/viewcontent.cgi?article=2532&context=fac_journ |
_version_ |
1766008237186875392 |