Titlebar

Export bibliographic data
Literature by the same author
plus on the publication server
plus at Google Scholar

 

P-wave velocity changes in freezing hard low-porosity rocks : a laboratory-based time-average model

Title data

Draebing, Daniel ; Krautblatter, Michael:
P-wave velocity changes in freezing hard low-porosity rocks : a laboratory-based time-average model.
In: The Cryosphere. Vol. 6 (2012) Issue 5 . - pp. 1163-1174.
ISSN 1994-0424
DOI: https://doi.org/10.5194/tc-6-1163-2012

Project information

Project title:
Project's official titleProject's id
Influences of snow cover on thermal and mechanic processes in steep permafrost rockwallsNo information

Project financing: Deutsche Forschungsgemeinschaft (KR 3912/1-1)

Abstract in another language

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 (< 10%) metamorphic, magmatic and sedimentary rock samples from permafrost sites with a natural texture (> 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.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Permafrost; Seismic; Periglacial processes
Institutions of the University: Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Geomorphology
Result of work at the UBT: No
DDC Subjects: 500 Science > 550 Earth sciences, geology
Date Deposited: 08 Apr 2019 09:51
Last Modified: 08 Apr 2019 09:51
URI: https://eref.uni-bayreuth.de/id/eprint/48599