Research of the Kaakhem system of active faults in Tuva: segmentation and model of specific earthquakes

The marks of four powerful seismic activations from several strongest earthquakes for this zone are considered. Four earthquakes that occurred 800-1000, 1800-2100 (the Khoptinsky fault), 2500-2800 and 3400-3600 (the Shuysky fault) years ago were catastrophic. The value of one-act displacements reaches 4 m, and the length of the segments is 40 km. This suggests that the magnitude of earthquakes reached M = 7.5. Weaker earthquakes with M = 6.5-7.0 also occurred during the periods of seismic activations but this is the other issue for considering. Such events at each seismic activation included different segments, i.e. occurred in different parts of the Kaakhem fault system located about100 km apart. The last earthquakes in the Kaakhem fault system occurred in 2011-2012. Seismic fractures in these earthquake centers occurred within small morphostructures. Displacements along the fractures furthered the direction of these morphostructures for a long time. Further seismic fractures clearly fit into the existing morphostructures which points the relevance of morphostructural analysis use in seismic hazard rating within the Altai-Sayan seismically active region.

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