Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques
Automated monitoring of freeze-thaw cycles and fracture propagation in mountain rockwalls is needed to provide early warning about rockfall hazards. Conventional geoelectrical methods such as electrical resistivity tomography (ERT) are limited by large and variable ohmic contact resistances, requiri...
Published in: | Journal of Geophysical Research: Earth Surface |
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Online Access: | https://escholarship.org/uc/item/7h30b8mb https://doi.org/10.1002/2016jf003948 |
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ftcdlib:oai:escholarship.org:ark:/13030/qt7h30b8mb 2024-09-15T18:11:42+00:00 Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques Murton, Julian B Kuras, Oliver Krautblatter, Michael Cane, Tim Tschofen, Dominique Uhlemann, Sebastian Schober, Sandra Watson, Phil 2309 - 2332 2016-12-01 https://escholarship.org/uc/item/7h30b8mb https://doi.org/10.1002/2016jf003948 unknown eScholarship, University of California qt7h30b8mb https://escholarship.org/uc/item/7h30b8mb doi:10.1002/2016jf003948 public Journal of Geophysical Research Earth Surface, vol 121, iss 12 Earth Sciences article 2016 ftcdlib https://doi.org/10.1002/2016jf003948 2024-06-28T06:28:19Z Automated monitoring of freeze-thaw cycles and fracture propagation in mountain rockwalls is needed to provide early warning about rockfall hazards. Conventional geoelectrical methods such as electrical resistivity tomography (ERT) are limited by large and variable ohmic contact resistances, requiring galvanic coupling with metal electrodes inserted into holes drilled into rock, and which can be loosened by rock weathering. We report a novel experimental methodology that combined capacitive resistivity imaging (CRI), ERT, and microseismic event recording to monitor freeze-thaw of six blocks of hard and soft limestones under conditions simulating an active layer above permafrost and seasonally frozen rock in a nonpermafrost environment. Our results demonstrate that the CRI method is highly sensitive to freeze-thaw processes; it yields property information equivalent to that obtained with conventional ERT and offers a viable route for nongalvanic long-term geoelectrical monitoring, extending the benefits of the methodology to soft/hard rock environments. Contact impedances achieved with CRI are less affected by seasonal temperature changes, the aggregate state of the pore water (liquid or frozen), and the presence of low-porosity rock with high matrix resistivities than those achieved with ERT. Microseismic monitoring has the advantage over acoustic emissions that events were recorded in relevant field distances of meters to decameters from cracking events. For the first time we recorded about 1000 microcracking events and clustered them in four groups according to frequency and waveform. Compared to previous studies, mainly on ice-cracking in glaciers, the groups are attributed to single- or multiple-stage cracking events such as crack coalescence. Article in Journal/Newspaper Ice permafrost University of California: eScholarship Journal of Geophysical Research: Earth Surface 121 12 2309 2332 |
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University of California: eScholarship |
op_collection_id |
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unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Murton, Julian B Kuras, Oliver Krautblatter, Michael Cane, Tim Tschofen, Dominique Uhlemann, Sebastian Schober, Sandra Watson, Phil Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
topic_facet |
Earth Sciences |
description |
Automated monitoring of freeze-thaw cycles and fracture propagation in mountain rockwalls is needed to provide early warning about rockfall hazards. Conventional geoelectrical methods such as electrical resistivity tomography (ERT) are limited by large and variable ohmic contact resistances, requiring galvanic coupling with metal electrodes inserted into holes drilled into rock, and which can be loosened by rock weathering. We report a novel experimental methodology that combined capacitive resistivity imaging (CRI), ERT, and microseismic event recording to monitor freeze-thaw of six blocks of hard and soft limestones under conditions simulating an active layer above permafrost and seasonally frozen rock in a nonpermafrost environment. Our results demonstrate that the CRI method is highly sensitive to freeze-thaw processes; it yields property information equivalent to that obtained with conventional ERT and offers a viable route for nongalvanic long-term geoelectrical monitoring, extending the benefits of the methodology to soft/hard rock environments. Contact impedances achieved with CRI are less affected by seasonal temperature changes, the aggregate state of the pore water (liquid or frozen), and the presence of low-porosity rock with high matrix resistivities than those achieved with ERT. Microseismic monitoring has the advantage over acoustic emissions that events were recorded in relevant field distances of meters to decameters from cracking events. For the first time we recorded about 1000 microcracking events and clustered them in four groups according to frequency and waveform. Compared to previous studies, mainly on ice-cracking in glaciers, the groups are attributed to single- or multiple-stage cracking events such as crack coalescence. |
format |
Article in Journal/Newspaper |
author |
Murton, Julian B Kuras, Oliver Krautblatter, Michael Cane, Tim Tschofen, Dominique Uhlemann, Sebastian Schober, Sandra Watson, Phil |
author_facet |
Murton, Julian B Kuras, Oliver Krautblatter, Michael Cane, Tim Tschofen, Dominique Uhlemann, Sebastian Schober, Sandra Watson, Phil |
author_sort |
Murton, Julian B |
title |
Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
title_short |
Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
title_full |
Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
title_fullStr |
Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
title_full_unstemmed |
Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
title_sort |
monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
publisher |
eScholarship, University of California |
publishDate |
2016 |
url |
https://escholarship.org/uc/item/7h30b8mb https://doi.org/10.1002/2016jf003948 |
op_coverage |
2309 - 2332 |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_source |
Journal of Geophysical Research Earth Surface, vol 121, iss 12 |
op_relation |
qt7h30b8mb https://escholarship.org/uc/item/7h30b8mb doi:10.1002/2016jf003948 |
op_rights |
public |
op_doi |
https://doi.org/10.1002/2016jf003948 |
container_title |
Journal of Geophysical Research: Earth Surface |
container_volume |
121 |
container_issue |
12 |
container_start_page |
2309 |
op_container_end_page |
2332 |
_version_ |
1810449277890068480 |