On the fluid-metamorphic regime of deep fault zones (in connection with the article by G.G. Kocharyan and I.V. Shatunov “topical issues in hydrogeology of seismogenic fault zones”)

To a large extent, the deep fluid regime plays a key role in seismicity, aseismic deformation of the lithosphere, and ore and oil genesis processes. An informative detailed analysis of the hydrogeology of shallow fault zones is presented in (Kocharyan and Shatunov, 2024), where it is noted that the nature of fluid dynamics of deep faults is poorly understood. In this article, the main attention is paid to the problems of describing deep fault zones, and a number of contradictions arising from this consideration are pointed out. It is shown that the challenges of such a description are largely eliminated by considering the processes of metamorphism and related anomalies in the physical properties of the Earth’s interior. A further refinement of the proposition that earthquakes occurring at different depths have different physical mechanisms is presented.