Electrical and seismic response of saline permafrost soil during freeze - Thaw transition
We conducted laboratory studies on the geophysical signals from Arctic saline permafrost soils to help understand the physical and mechanical processes during freeze-thaw cycles. Our results revealed low electrical resistivity (<20Ωm) and elastic moduli (7.7GPa for Young’s modulus and 2.9GPa for...
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ftcdlib:oai:escholarship.org/ark:/13030/qt2wx7k6xf 2023-05-15T15:16:30+02:00 Electrical and seismic response of saline permafrost soil during freeze - Thaw transition Wu, Yuxin Nakagawa, Seiji Kneafsey, Timothy J Dafflon, Baptiste Hubbard, Susan 2017-01-01 application/pdf https://escholarship.org/uc/item/2wx7k6xf unknown eScholarship, University of California qt2wx7k6xf https://escholarship.org/uc/item/2wx7k6xf public Saline permafrost Electrical resistivity Induced polarization Seismic property Freeze - thaw Unfrozen water content Geochemistry & Geophysics Geophysics Geomatic Engineering article 2017 ftcdlib 2021-11-15T18:16:52Z We conducted laboratory studies on the geophysical signals from Arctic saline permafrost soils to help understand the physical and mechanical processes during freeze-thaw cycles. Our results revealed low electrical resistivity (<20Ωm) and elastic moduli (7.7GPa for Young’s modulus and 2.9GPa for shear modulus) at temperatures down to −10°C, indicating the presence of a significant amount of unfrozen saline water under the current field conditions. The spectral induced polarization signal showed a systematic shift during the freezing process, affected by concurrent changes of temperature, salinity, and ice formation. An anomalous induced polarization response was first observed during the transient period of supercooling and the onset of ice nucleation. Seismic measurements showed a characteristic maximal attenuation at the temperatures immediately below the freezing point, followed by a decrease with decreasing temperature. The calculated elastic moduli showed a non-hysteric response during the freeze – thaw cycle, which was different from the concurrently measured electrical resistivity response where a differential resistivity signal is observed depending on whether the soil is experiencing freezing or thawing. The differential electrical resistivity signal presents challenges for unfrozen water content estimation based on Archie’s law. Using an improved formulation of Archie’s law with a variable cementation exponent, the unfrozen water content estimation showed a large variation depending on the choice of the resistivity data during either a freezing or thawing cycle. Combining the electrical and seismic results, we suggest that, rather than a large hysteresis in the actual unfrozen water content, the shift of the resistivity response may reflect the changes of the distribution pattern of the unfrozen water (or ice) in the soil matrix during repeated freeze and thaw processes. Collectively, our results provide an improved petrophysical understanding of the physical and mechanical properties of saline permafrost during freeze – thaw transitions, and suggest that large uncertainty may exist when estimating the unfrozen water content using electrical resistivity data. Article in Journal/Newspaper Arctic Ice permafrost University of California: eScholarship Arctic |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Saline permafrost Electrical resistivity Induced polarization Seismic property Freeze - thaw Unfrozen water content Geochemistry & Geophysics Geophysics Geomatic Engineering |
spellingShingle |
Saline permafrost Electrical resistivity Induced polarization Seismic property Freeze - thaw Unfrozen water content Geochemistry & Geophysics Geophysics Geomatic Engineering Wu, Yuxin Nakagawa, Seiji Kneafsey, Timothy J Dafflon, Baptiste Hubbard, Susan Electrical and seismic response of saline permafrost soil during freeze - Thaw transition |
topic_facet |
Saline permafrost Electrical resistivity Induced polarization Seismic property Freeze - thaw Unfrozen water content Geochemistry & Geophysics Geophysics Geomatic Engineering |
description |
We conducted laboratory studies on the geophysical signals from Arctic saline permafrost soils to help understand the physical and mechanical processes during freeze-thaw cycles. Our results revealed low electrical resistivity (<20Ωm) and elastic moduli (7.7GPa for Young’s modulus and 2.9GPa for shear modulus) at temperatures down to −10°C, indicating the presence of a significant amount of unfrozen saline water under the current field conditions. The spectral induced polarization signal showed a systematic shift during the freezing process, affected by concurrent changes of temperature, salinity, and ice formation. An anomalous induced polarization response was first observed during the transient period of supercooling and the onset of ice nucleation. Seismic measurements showed a characteristic maximal attenuation at the temperatures immediately below the freezing point, followed by a decrease with decreasing temperature. The calculated elastic moduli showed a non-hysteric response during the freeze – thaw cycle, which was different from the concurrently measured electrical resistivity response where a differential resistivity signal is observed depending on whether the soil is experiencing freezing or thawing. The differential electrical resistivity signal presents challenges for unfrozen water content estimation based on Archie’s law. Using an improved formulation of Archie’s law with a variable cementation exponent, the unfrozen water content estimation showed a large variation depending on the choice of the resistivity data during either a freezing or thawing cycle. Combining the electrical and seismic results, we suggest that, rather than a large hysteresis in the actual unfrozen water content, the shift of the resistivity response may reflect the changes of the distribution pattern of the unfrozen water (or ice) in the soil matrix during repeated freeze and thaw processes. Collectively, our results provide an improved petrophysical understanding of the physical and mechanical properties of saline permafrost during freeze – thaw transitions, and suggest that large uncertainty may exist when estimating the unfrozen water content using electrical resistivity data. |
format |
Article in Journal/Newspaper |
author |
Wu, Yuxin Nakagawa, Seiji Kneafsey, Timothy J Dafflon, Baptiste Hubbard, Susan |
author_facet |
Wu, Yuxin Nakagawa, Seiji Kneafsey, Timothy J Dafflon, Baptiste Hubbard, Susan |
author_sort |
Wu, Yuxin |
title |
Electrical and seismic response of saline permafrost soil during freeze - Thaw transition |
title_short |
Electrical and seismic response of saline permafrost soil during freeze - Thaw transition |
title_full |
Electrical and seismic response of saline permafrost soil during freeze - Thaw transition |
title_fullStr |
Electrical and seismic response of saline permafrost soil during freeze - Thaw transition |
title_full_unstemmed |
Electrical and seismic response of saline permafrost soil during freeze - Thaw transition |
title_sort |
electrical and seismic response of saline permafrost soil during freeze - thaw transition |
publisher |
eScholarship, University of California |
publishDate |
2017 |
url |
https://escholarship.org/uc/item/2wx7k6xf |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Ice permafrost |
genre_facet |
Arctic Ice permafrost |
op_relation |
qt2wx7k6xf https://escholarship.org/uc/item/2wx7k6xf |
op_rights |
public |
_version_ |
1766346805353644032 |