Fracture localization along faults with spatially varying friction

TLDR

Opening‑mode splay fractures cluster near fault tips, and their spatial distribution along faults influences fluid flow and reveals mechanical faulting processes, while slip gradients create stress concentrations that promote fracture development and spatial variations in frictional strength can reduce stress singularities at fault tips, encouraging multiple inward fractures. The study examines the conditions that promote splay crack localization using analytical and numerical fault models. Single splay fractures form at abrupt friction changes or fault tips when tip friction falls below a critical value, while a linearly increasing friction coefficient toward the tip promotes multiple fractures in a broad zone near the tip. The authors find that abrupt friction changes or low tip friction trigger single splay fractures, whereas a linearly increasing friction gradient toward the tip leads to multiple fractures in.

Abstract

Opening‐mode splay fractures have been observed within clusters near fault tips. The spatial distribution of splay fractures along faults influences fluid flow and lends insight into the mechanical processes of faulting. Slip gradients along faults produce stress concentrations which promote the development of opening‐mode splay fractures along faults. Since the slip distribution depends on the distribution of frictional strength along faults, spatial variations in the frictional properties may influence fracture localization. Variations in friction coefficient along faults can reduce the stress singularities at fault tips and promote the development of multiple fractures inwards from the fault tips. The conditions that promote splay crack localization are examined using analytical and numerical fault models. Single splay fractures develop at locations of abrupt friction coefficient change and/or at fault tips when the friction coefficient near the tips is less than a critical value. Fault models with linearly increasing friction coefficient toward the fault tip promote the development of multiple splay fractures within broad zones near the tip.