Work

From fragmentation to fault zone architecture as a structural framework for fault weakening

Year: 2026

Type: article

Abstract: Earthquake nucleation is governed by the evolution of fault zone structure, yet the physical mechanisms linking grain-scale processes to macroscopic weakening remain elusive. Here we use discrete element simulations of quartz-rich gouge in which angular grains fragment dynamically, revealing a robust strain–damage law in which damage accumulates as grains are consumed. Grain size dictates the geometry and timing of localization, while fragmentation enhances compaction and promotes the emergence of a dominant Principal Slip Zone (PSZ). As comminution approaches a saturation state (i.e. minimum grain size), localization can migrate to competing bands, providing a mechanical explanation for overprinted shear fabrics in experiments and natural faults. By linking fragmentation, porosity evolution, and the resulting shear localization, our results provide a local fragmentation state variable for constitutive laws that couple grain-size evolution to fault weakening and the conditions for earthquake nucleation. This study combines simulations and laboratory data to show how grains breaking inside fault gouge reshape fault-zone architecture, focus slip into narrow bands and help faults weaken during deformation.

Source: Nature Communications

DOI: 10.1038/s41467-026-78254-w

Authors: Nathalie Casas, Guilhem Mollon, Marco Maria Scuderi

Institutions: Sapienza University of Rome, Centre National de la Recherche Scientifique, Laboratoire de Mécanique des Contacts et des Structures, Institut National des Sciences Appliquées de Lyon

Language: English

Topic: earthquake and tectonic studies

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $6,990

OpenAlex ID: W7222748436

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