Seismic events miss important kinematically governed grain scale mechanisms during shear failure of porous rock

2022/10/18 by Alexis Cartwright‐Taylor, Maria‐Daphne Mangriotis, Ian Main +11 · 1 voice · 2 citations
Earth and Planetary Sciences · Engineering · Environmental Science · #Landslides and related hazards #Rock Mechanics and Modeling #earthquake and tectonic studies

paper · pdf · doi:10.1038/s41467-022-33855-z

openalex publication_date 2022/10/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31

Abstract

Catastrophic failure in brittle, porous materials initiates when smaller-scale fractures localise along an emergent fault zone in a transition from stable crack growth to dynamic rupture. Due to the rapid nature of this critical transition, the precise micro-mechanisms involved are poorly understood and difficult to image directly. Here, we observe these micro-mechanisms directly by controlling the microcracking rate to slow down the transition in a unique rock deformation experiment that combines acoustic monitoring (sound) with contemporaneous in-situ x-ray imaging (vision) of the microstructure. We find seismic amplitude is not always correlated with local imaged strain; large local strain often occurs with small acoustic emissions, and vice versa. Local strain is predominantly aseismic, explained in part by grain/crack rotation along an emergent shear zone, and the shear fracture energy calculated from local dilation and shear strain on the fault is half of that inferred from the bulk deformation.

Citations

• Simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object
• The failure of brittle porous solids under compressive stress states
• Dynamics of an expanding circular fault
• Fracture in Westerly Granite under AE Feedback and Constant Strain Rate Loading: Nucleation, Quasi-static Propagation, and the Transition to Unstable Fracture Propagation

Cited by

• Heitt Mjölnir: a heated miniature triaxial apparatus for 4D synchrotron microtomography
• Using internal standards in time-resolved X-ray micro-computed tomography to quantify grain-scale developments in solid-state mineral reactions

Discussions

• The emergent development of brittle shear failure in rocks occurs too fast for even synchrotron microCT to capture ... or does it? We combined acoustic emissions and X-rays to image this process doi.o [bsky, 0 points, 1 comments]