Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques
©2016. The Authors. 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...
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Language: | English |
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ftcdlib:qt7h30b8mb 2023-05-15T16:37:52+02:00 Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques Murton, JB Kuras, O Krautblatter, M Cane, T Tschofen, D Uhlemann, S Schober, S Watson, P 2309 - 2332 2016-12-01 application/pdf http://www.escholarship.org/uc/item/7h30b8mb english eng eScholarship, University of California qt7h30b8mb http://www.escholarship.org/uc/item/7h30b8mb public Murton, JB; Kuras, O; Krautblatter, M; Cane, T; Tschofen, D; Uhlemann, S; et al.(2016). Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques. Journal of Geophysical Research: Earth Surface, 121(12), 2309 - 2332. doi:10.1002/2016JF003948. Lawrence Berkeley National Laboratory: Retrieved from: http://www.escholarship.org/uc/item/7h30b8mb article 2016 ftcdlib https://doi.org/10.1002/2016JF003948 2018-09-14T22:51:34Z ©2016. The Authors. 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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Open Polar |
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University of California: eScholarship |
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ftcdlib |
language |
English |
description |
©2016. The Authors. 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, JB Kuras, O Krautblatter, M Cane, T Tschofen, D Uhlemann, S Schober, S Watson, P |
spellingShingle |
Murton, JB Kuras, O Krautblatter, M Cane, T Tschofen, D Uhlemann, S Schober, S Watson, P Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques |
author_facet |
Murton, JB Kuras, O Krautblatter, M Cane, T Tschofen, D Uhlemann, S Schober, S Watson, P |
author_sort |
Murton, JB |
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 |
http://www.escholarship.org/uc/item/7h30b8mb |
op_coverage |
2309 - 2332 |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_source |
Murton, JB; Kuras, O; Krautblatter, M; Cane, T; Tschofen, D; Uhlemann, S; et al.(2016). Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques. Journal of Geophysical Research: Earth Surface, 121(12), 2309 - 2332. doi:10.1002/2016JF003948. Lawrence Berkeley National Laboratory: Retrieved from: http://www.escholarship.org/uc/item/7h30b8mb |
op_relation |
qt7h30b8mb http://www.escholarship.org/uc/item/7h30b8mb |
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 |
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1766028172750487552 |