ОN THE DEVELOPMENT OF A SEISMOGEOLOGICAL APPROACH TO THE MEDIUM-TERM FORECAST OF EARTHQUAKES IN THE BAIKAL RIFT ZONE

The paper considers the results of many years of research related to the development of an approach to the medium-term earthquake prediction within the Baikal Rift Zone in order to more effectively ensure the seismic safety of the local population and infrastructure. To analyze the seismic regime at the stages of preparation of dangerous earthquakes with K≥13 (M≥5.0), the developed geoinformation system “Prediction” based on the well-known method of pattern recognition was used. In order to better understand the geological conditions for the preparation of earthquake sources, full-scale experiments on the type of slider models in the Angara fault zone were carried out together with specialists from the institutes of the Russian Academy of Sciences in order to determine the geomechanical conditions for the occurrence of seismic oscillation sources. As a result, a two-stage seismic event preparation regime was revealed, which was further used to improve the medium-term forecast. The study of exhumed paleo-earthquake sources yielded important geological and geophysical data on the thermodynamic and geomechanical conditions for the preparation of paleo-earthquake sources in the zone of the marginal suture of the Siberian Craton, 
which occurred in the bowels of the earth›s crust during past epochs of seismotectonic activations. The collected information was used in the development of methods for man-made impacts on seismically hazardous fault segments in order to reduce their seismic potential. When analyzing the totality of the collected materials, it was found that the most informative criteria for identifying the places of preparation of the emerging sources of dangerous earthquakes are: segments of high-ranking seismically active faults or their intersection nodes, as well as seismic gaps in the epicentral field in combination with signs of increasing seismic activity on their periphery that occurs in the last decade. As an example, the data of the medium-term forecast for the period 2019-2022 are given. It has been established that the percentage of epicenters of occurred earthquakes with the specified energy falling into their waiting areas, indicated in the report sent in 2019 to the Ministry of Emergency Situations of the Irkutsk Region, is 76%. The authors are making efforts to improve the approach to improving the medium-term forecast in relation to the features of the seismic regime in the BRZ based on the use of an experimentally substantiated two-stage earthquake preparation model to obtain formalized estimates of the other two basic forecast parameters “E” - energy and “T” - event waiting time. In conclusion, conclusions are presented about the increased importance of the medium-term forecast in seismic hazard assessments, as well as about the existence of 
ways to dampen the destructive consequences of future earthquakes using man-made impacts on the fault segments identified during the forecast with signs of preparation of dangerous earthquakes in the coming years.