Active Faulting in the Earth’s Crust of the Baikal Rift System Based on the Earthquake Focal Mechanisms

Abstract

The destruction of the lithosphere with the formation of fault zones is one of the leading geological processes determining the structure of the continents, both in the past and at the present stage. Seismicity providing information on the structure and dynamics of formation of large fault zones in real time reflects the modern fault formation in the crust. For its study, both the epicentral field of earthquakes (see, for example, Sherman 2009) and the data on the position of their hypocenters are actively used (see, for example, Kaven and Polland 2013). To determine the orientation of modern faults of various orders, one can also use data on the earthquake focal mechanism solutions preliminarily distinguishing the true fault planes in the source. In the case of strong earthquakes, the geological data (the outcrop of the fault on the surface, the existing of faults with similar geometry, etc.), the data on the orientation of the aftershock field, the shape of the first isoseits, and other data are indirect features that help to choose one plane or another as the true fault plane. These approaches are inapplicable in study of weak earthquakes (magnitude M ≤ 4.0) and the only information available on them is concerned with their waveforms.