Shear Bands Triggered by Solitary Porosity Waves in Deforming Fluid‐Saturated Porous Media.

The interplay between compaction‐driven fluid flow and plastic yielding within porous media is investigated through numerical modeling. We establish a framework for understanding the dynamics of fluid flow in deforming porous materials that corresponds to the equations describing solitary porosity wave propagation. A concise derivation of the coupled fluid flow and poro‐viscoelastoplastic matrix behavior is presented, revealing a connection to Biot's equations of poroelasticity and Gassmann's theory in the elastic limit. Our findings demonstrate that fluid overpressure resulting from channelized fluid flow initiates the formation of new shear zones. Through three‐dimensional simulations, we observe that the newly formed shear zones exhibit a parabolic shape. Furthermore, plasticity exerts a significant influence on both the velocity of fluid flow and the shape of fluid channels. Importantly, our study highlights the potential of spontaneous channeling of porous fluids to trigger seismic events by activating both new and pre‐existing faults. Plain Language Summary: In this study, we looked at how fluids move through porous rocks and how they interact with the solid frame of the rocks. The physics was explored in two‐ and three‐dimensions by leveraging the power of high‐performance computing (HPC) based on graphical processing units (GPU). We found that two key processes occur at the same time: fluid flow gets concentrated into channels due to the changing pressure and interaction with the solid material, and it also forms dike‐like structures as it pushes into newly formed shear zones. Importantly, our study highlights the potential of spontaneous channeling of porous fluids to trigger seismic events by activating both new and pre‐existing faults. This research underscores the complex relationship between fluid flow dynamics and geomechanical processes, offering insights into the mechanisms underlying earthquake initiation. Key Points: We present the numerical modeling of fully coupled fluid flow and poro‐viscoelastoplastic matrix flow with decompaction weakeningWe show that fluid overpressure at the tip of the fluid flow channel triggers the development of non‐symmetric shear bandsWe discover that plastic yielding accelerates the fluid flow and modifies the fluid flow pattern [ABSTRACT FROM AUTHOR]