The influence of spatial resolution and noise on fracture network properties calculated from X-ray microtomography data

McBeck, Jessica; Cordonnier, B.; Renard, François

doi:10.1016/j.ijrmms.2021.104922

Cited by 7 publications

(4 citation statements)

References 63 publications

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“…The data sets were processed, segmented, analyzed and visualized in Avizo (Thermo Fischer Scientific). Depending on the noise filtering algorithm, the segmentation method, and the interconnectivity options between voxels employed, final porosity values can vary (see Kirilova et al., 2020; McBeck et al., 2021 and references therein). All SμCT volumes were processed similarly with the same workflow recipe.…”

Section: Methodsmentioning

confidence: 99%

Dynamic Evolution of Porosity in Lower‐Crustal Faults During the Earthquake Cycle

et al. 2023

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Earthquake‐induced fracturing of the dry and strong lower crust can transiently increase permeability for fluids to flow and trigger metamorphic and rheological transformations. However, little is known about the porosity that facilitates these transformations. We analyzed microstructures that have recorded the mechanisms generating porosity in the lower crust from a pristine pseudotachylyte (solidified earthquake‐derived frictional melt) and a mylonitized pseudotachylyte from Lofoten, Norway to understand the evolution of fluid pathways from the coseismic to the post‐ and interseismic stages of the earthquake cycle. Porosity is dispersed and poorly interconnected within the pseudotachylyte vein (0.14 vol%), with a noticeably increased amount along garnet grain boundaries (0.25 ‐ 0.41 vol%). This porosity formed due to a net negative volume change at the grain boundary when garnet overgrows the pseudotachylyte matrix. Efficient healing of the damage zone by fluid‐assisted growth of feldspar neoblasts resulted in the preservation of only a few but relatively large interconnected pores along coseismic fractures (0.03 vol% porosity). In contrast, porosity in the mylonitized pseudotachylyte is dramatically reduced (0.02 vol% overall), because of the efficient precipitation of phases (amphibole, biotite and feldspars) into transient pores during grain‐size sensitive creep. Porosity reduction on the order of >85 % may be a contributing factor in shear zone hardening, potentially leading to the development of new pseudotachylytes overprinting the mylonites. Our results show that earthquake‐induced rheological weakening of the lower crust is intermittent and occurs when a fluid can infiltrate a transiently permeable shear zone, thereby facilitating diffusive mass transfer and creep.

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Section: Methodsmentioning

confidence: 99%

Dynamic Evolution of Porosity in Lower‐Crustal Faults During the Earthquake Cycle

et al. 2023

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“…Using these three‐dimensional volumes, we segment the solid rock from the pores and fractures. We use an algorithm similar to Otsu's thresholding technique to identify a global threshold between the solid material and the fractures and pores (McBeck et al., 2021). This thresholding technique is robust to noise (McBeck et al., 2021) and produces segmented scans with porosity similar to measured values (Renard et al., 2018).…”

Section: Methodsmentioning

confidence: 99%

Deriving Three‐Dimensional Properties of Fracture Networks From Two‐Dimensional Observations in Rocks Approaching Failure Under Triaxial Compression: Implications for Fluid Flow

McBeck

Renard

2022

Water Resources Research

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“…We remove remaining noise in the three-dimensional data using the software Avizo3D TM , including the application of a non-local means filter [58]. We then segment the solid rock from the pores and fractures using an algorithm similar to Otsu's thresholding technique to identify a global threshold between the solid material and the fractures and pores [59]. This thresholding technique is not strongly influenced by noise [59] and produces segmented scans with porosity similar to values measured with sample imbibition [60].…”

Section: Experimental Designmentioning

confidence: 99%

“…We then segment the solid rock from the pores and fractures using an algorithm similar to Otsu's thresholding technique to identify a global threshold between the solid material and the fractures and pores [59]. This thresholding technique is not strongly influenced by noise [59] and produces segmented scans with porosity similar to values measured with sample imbibition [60]. We then apply several processing techniques to the segmented scans in Avizo3D TM , including Label Analysis, that identify individual fractures using connected clusters of voxels, and calculate the geometric characteristics and orientation of fractures relative to the vertical and 𝜎 !…”

Section: Experimental Designmentioning

confidence: 99%

Deformation evolves from shear to extensile in rocks due to energy optimization

McBeck

Cordonnier

Cooke

et al. 2023

Preprint

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Determining how fracture network development leads to macroscopic failure in heterogeneous materials may help estimate the timing of failure in rocks in the upper crust as well as in engineered structures. The proportion of extensile and shear deformation produced by fracture development indicates the appropriate failure criteria to apply, and thus is a key constraint in such an effort. Here, we measure the volume proportion of extensile and shear fractures using the orientation of the fractures that develop in triaxial compression experiments in which fractures are identified using dynamic in situ synchrotron X-ray imaging. The fracture orientations transition from shear to extensile approaching macroscopic, system-size failure. Numerical models suggest that this transition occurs because the fracture networks evolve in order to optimize the total mechanical efficiency of the system. Our results provide a physical interpretation of the empirical internal friction coefficient in rocks.

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The influence of spatial resolution and noise on fracture network properties calculated from X-ray microtomography data

Cited by 7 publications

References 63 publications

Dynamic Evolution of Porosity in Lower‐Crustal Faults During the Earthquake Cycle

Dynamic Evolution of Porosity in Lower‐Crustal Faults During the Earthquake Cycle

Deriving Three‐Dimensional Properties of Fracture Networks From Two‐Dimensional Observations in Rocks Approaching Failure Under Triaxial Compression: Implications for Fluid Flow

Deformation evolves from shear to extensile in rocks due to energy optimization

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