Bedrock Fracture by Ice Segregation in Cold Regions

Murton, Julian B.; Peterson, Rorik; Ozouf, Jean‐Claude

doi:10.1126/science.1132127

Cited by 345 publications

(297 citation statements)

References 17 publications

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“…The formation of ice within rock is likely to be an important driver of near-surface frost weathering (Hallet et al, 1991) and rock damage at the depth of several meters (Murton et al, 2006), and in steep terrain, this process may be crucial for the slow preconditioning of rock fall from warming permafrost areas (Matsuoka and Murton, 2008;Gruber and Haeberli, 2007). However, the transfer of corresponding theoretical insight and laboratory evidence to natural conditions characterized by strong spatial and temporal heterogeneity of the rock properties (e.g.…”

Section: Introductionmentioning

confidence: 96%

Evidence of frost-cracking inferred from acoustic emissions in a high-alpine rock-wall

Amitrano

Gruber

Girard

2012

Earth and Planetary Science Letters

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Ice formation within rock is known to be an important driver of near-surface frost weathering as well as of rock damage at the depth of several meters, which may play a crucial role for the slow preconditioning of rock fall in steep permafrost areas. This letter reports results from an experiment where acoustic emission monitoring was used to investigate rock damage in a high-alpine rock-wall induced by natural thermal cycling and freezing/thawing. The analysis of the large catalog of events obtained shows (i) robust power-law distributions in the time and energy domains, a footprint of rock micro-fracturing activity induced by stresses arising from thermal variations and associated freezing/ thawing of rock; (ii) an increase in AE activity under sub-zero rock-temperatures, suggesting the importance of freezing-induced stresses. AE activity further increases in locations of the rock-wall that are prone to receiving melt water. These results suggest that the framework of further modeling studies (theoretical and numerical) should include damage, elastic interaction and poro-mechanics in order to describe freezing-related stresses. Keywords: frost-cracking acoustic emission mechanical weathering scaling properties a b s t r a c t Ice formation within rock is known to be an important driver of near-surface frost weathering as well as of rock damage at the depth of several meters, which may play a crucial role for the slow preconditioning of rock fall in steep permafrost areas. This letter reports results from an experiment where acoustic emission monitoring was used to investigate rock damage in a high-alpine rock-wall induced by natural thermal cycling and freezing/thawing. The analysis of the large catalog of events obtained shows (i) robust power-law distributions in the time and energy domains, a footprint of rock micro-fracturing activity induced by stresses arising from thermal variations and associated freezing/ thawing of rock; (ii) an increase in AE activity under sub-zero rock-temperatures, suggesting the importance of freezing-induced stresses. AE activity further increases in locations of the rock-wall that are prone to receiving melt water. These results suggest that the framework of further modeling studies (theoretical and numerical) should include damage, elastic interaction and poro-mechanics in order to describe freezing-related stresses.

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Section: Introductionmentioning

confidence: 96%

Evidence of frost-cracking inferred from acoustic emissions in a high-alpine rock-wall

Amitrano

Gruber

Girard

2012

Earth and Planetary Science Letters

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“…In our system, samples cool from all outer faces which presumably act to seal the sample with ice. On the other hand, ice segregation along temperature gradients in fissured natural bedrock will cause suction up to several MPa (Murton et al, 2006;Walder and Hallet, 1985) and ice growth, and presumably cause a persistent elevated level of cryostatic stress similar to our laboratory setup. Figure 4a and b show an offset which is not explainable by Eq.…”

Section: Model Setup and Representativenessmentioning

confidence: 99%

“…A surpassing damage threshold or opening of microcracks could explain anisotropy increase. The pore pressure can be generated by the ice pressure building (Matsuoka, 1990;Vlahou and Worster, 2010) due to volumetric expansion of in situ water (Hall et al, 2002;Matsuoka and Murton, 2008) and ice segregation (Hallet, 2006;Murton et al, 2006;Walder and Hallet, 1985). In the laboratory, any open system allows water migration and enables ice segregation while closed systems with water-saturated samples favour volumetric expansion (Matsuoka, 1990).…”

Section: Model Setup and Representativenessmentioning

confidence: 99%

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

Draebing

Krautblatter

2012

The Cryosphere

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Abstract. 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 lowporosity (< 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, pwave 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 twophase-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.

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“…Slope failures in rock masses that develop along pre-existing discontinuities may occur due to various environmentally induced mechanisms such as high magnitude earthquakes (Rodriguez et al, 1999;Yagoda-Biran et al, 2010;Hatzor, 2003), pore pressure build-up in rock joints (Iverson, 2000;Veveakis et al, 2007), and freezing and thawing of water in joints (Matsuoka, 2008;Murton et al, 2006;Williams, 1995). These suggested mechanisms fail to describe time-dependent, thermally controlled sliding along discontinuities or opening of tensile fractures which may ultimately culminate in slope failure.…”

Section: Rationale On Causes Of Rock Failuresmentioning

confidence: 99%

Advancedmonitoring Systems for Landslide Risk Reduction in The'siq' of Petra (Jordan)

Delmonaco

Brini²,

Cesaro

2017

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:The UNESCO World Heritage Site of Petra is characterized by a spectacular geo-archaeological landscape that lead to its inscription as World Heritage Site in 1985. Petra is also a fragile site facing a wide diversity of risks, ranging from those posed by environmental factors as well as those attributed to tourism. In recent years, hazardous natural phenomena were registered as increasingly impacting the site, and most specifically the 'Siq', a 1.2 km naturally formed gorge serving as the only tourist entrance to the archaeological park, posing a major threat to cultural heritage and visitors. These recent events have prompted UNESCO Amman Office, in cooperation with the national authorities, to develop a strategy towards prevention and mitigation of instability phenomena at the 'Siq' and, thus, further contribute to the management and conservation of the site through the implementation of the multi-year Italian funded "Siq Stability" project Actions have been primarily focusing on the analysis of the stability conditions of the 'Siq' slopes, the installation of an integrated monitoring system and the definition and implementation of mitigation measures against rock instability. This paper reports a detailed description of the integrated monitoring system installed paying particular attention on the wireless monitoring devices and the EASA applications, which proved to be some of the most successful systems implemented in the framework of the project. Some preliminary results regarding the data retrieved, policies applied and actions taken to ensure longterm sustainability and capacity development of the national authorities are also reported.

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Bedrock Fracture by Ice Segregation in Cold Regions

Cited by 345 publications

References 17 publications

Evidence of frost-cracking inferred from acoustic emissions in a high-alpine rock-wall

Evidence of frost-cracking inferred from acoustic emissions in a high-alpine rock-wall

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

Advancedmonitoring Systems for Landslide Risk Reduction in The'siq' of Petra (Jordan)

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