THMC instabilities and the Multiphysics of Earthquakes
arXiv:1906.01116
The paper examines how coupled thermo‑hydro‑mechano‑chemical (THMC) processes can generate volumetric instabilities that precede shear failure in earthquakes, showing that cross‑diffusion can produce slow pressure waves whose resonance may trigger seismic slip.
Abstract
Theoretical approaches to earthquake instabilities propose shear dominated instabilities as a source mechanism. Here we take a fresh look at the role of possible volumetric instabilities preceding a shear instability. We investigate the phenomena that may prepare earthquake instabilities using coupling of Thermo-Hydro-Mechano-Chemical (THMC) reaction-diffusion equations in a THMC diffusion matrix. We show that the off-diagonal cross-diffusivities can give rise to cross-diffusion slow (no inertia) pressure waves and propose that a resonance phenomenon of the long-wavelength limit causes constructive interference and triggers the seismic moment release.
7 pages, 3 figures, 1 table