P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model
P-wave refraction seismics is a key method in permafrost research but its applicability to low-porosity rocks, which constitute alpine rock walls, has been denied in prior studies. These studies explain p-wave velocity changes in freezing rocks exclusively due to changing velocities of pore infill,...
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Copernicus Publications
2012
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Online Access: | https://doi.org/10.5194/tc-6-1163-2012 http://www.the-cryosphere.net/6/1163/2012/tc-6-1163-2012.pdf https://doaj.org/article/25f3bbca8c584718831b9d18b307fd19 |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:25f3bbca8c584718831b9d18b307fd19 2023-05-15T16:37:41+02:00 P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model D. Draebing M. Krautblatter 2012-10-01 https://doi.org/10.5194/tc-6-1163-2012 http://www.the-cryosphere.net/6/1163/2012/tc-6-1163-2012.pdf https://doaj.org/article/25f3bbca8c584718831b9d18b307fd19 en eng Copernicus Publications doi:10.5194/tc-6-1163-2012 1994-0416 1994-0424 http://www.the-cryosphere.net/6/1163/2012/tc-6-1163-2012.pdf https://doaj.org/article/25f3bbca8c584718831b9d18b307fd19 undefined The Cryosphere, Vol 6, Iss 5, Pp 1163-1174 (2012) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2012 fttriple https://doi.org/10.5194/tc-6-1163-2012 2023-01-22T17:32:58Z P-wave refraction seismics is a key method in permafrost research but its applicability to low-porosity rocks, which constitute alpine rock walls, has been denied in prior studies. These studies explain p-wave velocity changes in freezing rocks exclusively due to changing velocities of pore infill, i.e. water, air and ice. In existing models, no significant velocity increase is expected for low-porosity bedrock. We postulate, that mixing laws apply for high-porosity rocks, but freezing in confined space in low-porosity bedrock also alters physical rock matrix properties. In the laboratory, we measured p-wave velocities of 22 decimetre-large low-porosity ( 100 micro-fissures) from 25 °C to −15 °C in 0.3 °C increments close to the freezing point. When freezing, p-wave velocity increases by 11–166% perpendicular to cleavage/bedding and equivalent to a matrix velocity increase from 11–200% coincident to an anisotropy decrease in most samples. The expansion of rigid bedrock upon freezing is restricted and ice pressure will increase matrix velocity and decrease anisotropy while changing velocities of the pore infill are insignificant. Here, we present a modified Timur's two-phase-equation implementing changes in matrix velocity dependent on lithology and demonstrate the general applicability of refraction seismics to differentiate frozen and unfrozen low-porosity bedrock. Article in Journal/Newspaper Ice permafrost The Cryosphere Unknown The Cryosphere 6 5 1163 1174 |
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geo envir D. Draebing M. Krautblatter P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model |
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geo envir |
description |
P-wave refraction seismics is a key method in permafrost research but its applicability to low-porosity rocks, which constitute alpine rock walls, has been denied in prior studies. These studies explain p-wave velocity changes in freezing rocks exclusively due to changing velocities of pore infill, i.e. water, air and ice. In existing models, no significant velocity increase is expected for low-porosity bedrock. We postulate, that mixing laws apply for high-porosity rocks, but freezing in confined space in low-porosity bedrock also alters physical rock matrix properties. In the laboratory, we measured p-wave velocities of 22 decimetre-large low-porosity ( 100 micro-fissures) from 25 °C to −15 °C in 0.3 °C increments close to the freezing point. When freezing, p-wave velocity increases by 11–166% perpendicular to cleavage/bedding and equivalent to a matrix velocity increase from 11–200% coincident to an anisotropy decrease in most samples. The expansion of rigid bedrock upon freezing is restricted and ice pressure will increase matrix velocity and decrease anisotropy while changing velocities of the pore infill are insignificant. Here, we present a modified Timur's two-phase-equation implementing changes in matrix velocity dependent on lithology and demonstrate the general applicability of refraction seismics to differentiate frozen and unfrozen low-porosity bedrock. |
format |
Article in Journal/Newspaper |
author |
D. Draebing M. Krautblatter |
author_facet |
D. Draebing M. Krautblatter |
author_sort |
D. Draebing |
title |
P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model |
title_short |
P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model |
title_full |
P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model |
title_fullStr |
P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model |
title_full_unstemmed |
P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model |
title_sort |
p-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model |
publisher |
Copernicus Publications |
publishDate |
2012 |
url |
https://doi.org/10.5194/tc-6-1163-2012 http://www.the-cryosphere.net/6/1163/2012/tc-6-1163-2012.pdf https://doaj.org/article/25f3bbca8c584718831b9d18b307fd19 |
genre |
Ice permafrost The Cryosphere |
genre_facet |
Ice permafrost The Cryosphere |
op_source |
The Cryosphere, Vol 6, Iss 5, Pp 1163-1174 (2012) |
op_relation |
doi:10.5194/tc-6-1163-2012 1994-0416 1994-0424 http://www.the-cryosphere.net/6/1163/2012/tc-6-1163-2012.pdf https://doaj.org/article/25f3bbca8c584718831b9d18b307fd19 |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-6-1163-2012 |
container_title |
The Cryosphere |
container_volume |
6 |
container_issue |
5 |
container_start_page |
1163 |
op_container_end_page |
1174 |
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1766027987762806784 |