Seismic active zones in south Siberia, Russian Far East, and adjacent countries

Abstract

In consequence of our investigations curried out during 2009—2015 we established the connection of maximal seismic activity in South Siberia, Russian Far East and adjacent countries of central and East Asia with zones divided numerous crust blocks or lithosphere plates and blocks. The investigation was fulfilled with the main purpose of definition the most active interblock zones, distinguishing levels of the maximal seismic energy releasing in them and regularities of its dissipation. Main methods of studying were the analysis of active faults and epicenters distribution with correcting boundaries of blocks and interblock zones, the calculation of the seismic energy volume releasing in these zones with construction of deep seismic sections and graphs of energy dissipation along transects across majority of interblock zones. The most active zones coincide with boundaries such blocks as the Pamirs, Himalayas, Tien Shan, Tarim, Amurian, Japanese—Korean, North Japan, Kuril—Kamchatka and Okhotsk as well as with boundaries between some of these blocks with North Eurasian plate. The volume of energy releasing in mentioned zones reaches up to $1 \times 10{11-15}$~J, which is not far from the seismic energy releasing in subduction zones between the Pacific plate and Eurasia. Abnormal high seismic energy releasing depends of deep continuation of plate slabs in collision and subduction zones (the Pamirs, Himalayas, Kuril—Kamchatka), intensive displacements along strike-slips and thrusts due to collision processes and deep lithosphere unhomogeneity (Tien Shan, Altai), as well as of sharp changes of geodynamic conditions because of plate movement influence and supposed mantle plumes (North Mongolia, the Baikal Region). The examination of interblock zones is closely connected with the prediction of catastrophic earthquakes' possibility in some regions of central Asia that can be demonstrated at the example of the Kultuk earthquake in South Siberia and some others.