Seismogeological Conditions of Preparation of Hazardous Earthquakes in Fault Nodes

Abstract—The article discusses the results obtained from a detailed examination of the conditions for the preparation of hazardous earthquakes at different hierarchical levels: global, regional (Mongolia), and local (sections of the Baikal Rift Zone). Attention is paid to consideration of episodes of occurrence of instances of seismic activation in the vicinity of fault nodes of various scale levels, as well as geological and structural conditions that influence the modes of preparation of hazardous earthquake sources. study takes into account the linear dimensions and morphogenetic types of faults, their junction angles, specific features of the modern seismic regime, as well as information on seismic activity in the past. It has been established that due to the diverse conditions of dynamic interaction of faults at their junctions, strong earthquakes often occur in short time intervals and with their epicenters located close to each other. Such features complicate earthquake forecasting, since traditional ideas about the recurrence periods of earthquakes of a given magnitude are violated. Also, when forecasting earthquakes, additional problems arise concerning the estimates of the duration of earthquake expectation periods for short, medium and long time intervals. The authors have shown that in order to determine the duration of the waiting periods for hazardous earthquakes, it is currently possible to establish only probabilistic estimates of this parameter, linked to estimates of the predicted energy of upcoming events. To do this, it is necessary to conduct detailed observations of variations in the seismic regime of weak earthquakes at different crustal depths, and to record anomalous changes in the deformation regime and slip rate. It is also important to conduct geophysical observations of changes in parameters characteristic of the final stage of preparation of earthquake foci.