Three global-scale seismotectonic systems and the geoid

Abstract

Based on the comprehensive studies of the global seismicity and active tectonics, the global seismotectonics is summarized in three great systems: (1) the circum-Pacific seismotectonic system of deep subduction (system P); (2) the Atlantic seismotectonic system of mid-oceanic ridge rift (system A); and (3) the continental seismotectonic system of shear nets (system C). There is a high dynamic correlation between the distribution of these three systems on the Earth's surface and the deflection of the geoid relative to the ideal rotating ellipsoid. Comparative analyses of the three systems are made by using the data of tectonic deformation and earthquake mechanism. System A is characterized by planar extensional fractures. System P demonstrates obduction and overthrusting of the Atlantic (0°) hemisphere lithosphere towards the Pacific (180°) hemisphere lithosphere. System A represents dilatation of the south hemisphere, while system C indicates contraction of the north hemisphere. The dynamic connection between the circum-Antarctic oceanic ridge and system C is probably associated with the longitudinal flow of the mantle.