Cross-diffusion waves resulting from multiscale, multiphysics instabilities: application to earthquakes

Abstract. Theoretical approaches to earthquake instabilities propose shear-dominated source mechanisms. Here we take a fresh look at the role of possible volumetric preceding shear instability. We investigate phenomena that may prepare using coupling thermo-hydro-mechano-chemical reaction–diffusion equations in THMC diffusion matrix. show off-diagonal cross-diffusivities can give rise new class waves known as cross-diffusion or quasi-soliton waves. Their unique property is for critical conditions funnel wave energy into stationary focus from large small scale. rich solution space reaction–cross-diffusion approach recover classical Turing (periodic instabilities), Hopf bifurcations (spring-slider-like models), and Only lead extreme focussing short-wavelength short duration. The equivalent event ocean optical fibres leads appearance “rogue waves” high pulses light photonics. In context hydromechanical coupling, rogue would appear sudden fluid pressure spike. This spike likely cause unstable slip on pre-existing (near-critically stressed) fault acting trigger ultimate (shear) seismic moment release.