The seismic sequence in Central Italy (2016-2017) IV. - Clarifying some basic processes and concepts

We discuss the propagation processes of mechanical vibrations through a realistic non-homogeneous model of the Earth's crust, lithosphere and asthenosphere, specifically dealing with high frequency. The role of water is crucial, as - according to the interpretation which is here given - water is the likely cause for the formation of the Moho, for serpentinization and serpentosphere, and for the determination of the depth of the Asthenosphere-Lithosphere boundary (ALB). Serpentinization is one of the three main "engines" of "climate" and of the carbon cycle. The serpentosphere is the leading "carrier" of mechanical vibrations, also due to soaking by supercritical water (ScriW). Crustal phenomena largely derive from local propagation of mechanical vibration along "natural probes" from the serpentosphere through the overlying crust. Every "natural probe" is composed of a compact solid body, and its eventual fractures are soaked with ScriW. Seismic transmigration occurs crossing through every area, according to a few different processes, hence at comparably different speeds. Every different region has to be considered as a different case history, depending on the specific morphology of its crust and lithosphere, and on tectonism. The focal volume involved by every seismic phenomenon can be generalized and considered upon referring either to one single active fault, or to some large set of faults. It is shown how a generalized focal volume (gfv) can be approximately estimated by means of the seismic transmigration speed.