**3. OSC area in the Altai**

The area includes seismic active zones selecting the Altai Block from the North Eurasian Plate (NEP), West Mongolia and Sayany blocks within the south part of the Altai Republic, west part of the Tuva Republic in Russia and adjacent territory of northwest Mongolia (**Figure 1**). Its length is 356 km, width – 87-243 km and the total seismic energy volume achieves 1.70833·1016J (here and below we calculate cumulative energy volume during the course of 1966–2017 using for its calculation data from NEIC2019 catalog). Left- and right-lateral northwest slips with compression component predominate within the area as well as near latitudinal and northwest thrusts to the north and northwest. Maximal magnitudes (M) of earthquakes reach 5–8. The greatest seismic activity coincides with the boundary of the Altai Block and NEP, where the energy releasing increases up to 1011J. According to seismic cross section [1] right-lateral slips and thrusts to the northeast develop here in the depth 10-34 km. East on the boundary between West Mongolia and Sayany blocks left-lateral slips predominate in the depth of 8-32 km. Tectonic strain axis's have the northeast direction.

The heat flow (HF) value changes from 25 to 28 μW/m−2 within NEP near Novosibirsk, up to 55–96 to the south in the Altai Mountains [10]. Within the Mining Altai in east Kazakhstan HF is equal 29-61 μW/m−2. East on the boundary between West Mongolia and Sayany blocks HF value increases up to 80 μW/m−2 and larger. The International Terrestrial Reference Frame (ITRF2014) vectors of horizontal displacement have mainly east and southeast direction in stations near Novosibirsk (88.7–92.2°) with velocities 23.9–27.1 mm/y. However, the Altai Station north of Ust-Kamenogorsk fixes the displacement to 350° NW with the velocity 50 mm/y. The large gradient in the crust structure takes place at the boundary between Altai and Junggar blocks south from investigated region, where crust thickness decreases southeast from 55 to 60 down to 35-40 km [11]. Data on HF and the Global Navigation Satellite System (GNSS) velocities as well on S-wave velocities below give the representation of the crust and lithosphere activity, which can have the indirect connection with the seismicity level.

**5**

**Figure 1.**

*101*

*scheme as all others.*

*Tentative Intracontinental Seismic Activity in South Siberia and Russian Far East*

The geodynamic and seismicity data analysis allow supposing future earthquakes intensity within the Altai OSC area. Events with M7–8 are possible in the west quarter of this area within the Mountain Altai at the left bank of the Argug River, which is the Biya River left source, southwest from the Belyashi settlement. The hypocenters' predominant depth is there about 10-20 km that allows waiting mainly destructive events in this part of the area. Earthquakes with M5–6 are more

*J or 10−1 J. the minimal value is 10−7J, the maximal – 1014J. The black numerals in the scheme correspond to energy volume values in joules. Dotes with red figures near them correspond to values of the heat flow in*  μ*W/m−2. The total extensions of studied blocks see in the Figure 6. The authors of the chapter constructed this* 

*The OSC area situated in the northeast altai and west Sayany within seismic active zones selects the Altai block from NEP, Sayany and West Mongolia blocks. The summary legend for Figures 1, 2 and 3-5 includes boundaries of: 1 – Lithosphere plate, 2 – The same supposed, 3 – Transitional zone, 4 – Block, 5 – Interblock zone, 6 – OSC area (see the part 2). Other symbols: 7 – Active fault, 8 – River, 9 – State frontier, 10 – ITRF2014 (see the part 3) vectors of horizontal displacement, 11–14 – Mechanism in hypocenters after the centroid moment tensor (CMT2019) according to NEIC2018 seismological data (11 – Compression, 12 – Extension, 13 – Left-lateral slip, 14 – Right-lateral slip; the predominant orientation of segments in mechanism corresponds to a displacement direction), 15 – The magnitude scale of earthquake epicenters by CMT, 16 – The magnitude scale of earthquake epicenters, for which CMT2019 data are absent (according to NEIC seismological data). Thin lines with dark-blue circles correspond to tectonic stress axis's [9]. Green color fields, divided by isohypsis, show volumes of seismic energy releasing. Increasing color intensity corresponds to increasing energy volume on* 

This area embraces seismic active interblock zones separating the Sayany Block from NEP and from the Hangay Block in the east part of the Tuva Republic, southwest of Buryat Republic and adjacent part of north Mongolia (**Figure 2**). Its length is 350 km, width – 100-216 km and the total seismic energy volume achieves 1.805.11·1016J. The most intensive seismic energy releasing up to 109−11J characterizes

probable in future within the rest territory of the OSC area.

**4. OSC area in the East Sayany**

*DOI: http://dx.doi.org/10.5772/intechopen.95073*

*Tentative Intracontinental Seismic Activity in South Siberia and Russian Far East DOI: http://dx.doi.org/10.5772/intechopen.95073*

#### **Figure 1.**

*The OSC area situated in the northeast altai and west Sayany within seismic active zones selects the Altai block from NEP, Sayany and West Mongolia blocks. The summary legend for Figures 1, 2 and 3-5 includes boundaries of: 1 – Lithosphere plate, 2 – The same supposed, 3 – Transitional zone, 4 – Block, 5 – Interblock zone, 6 – OSC area (see the part 2). Other symbols: 7 – Active fault, 8 – River, 9 – State frontier, 10 – ITRF2014 (see the part 3) vectors of horizontal displacement, 11–14 – Mechanism in hypocenters after the centroid moment tensor (CMT2019) according to NEIC2018 seismological data (11 – Compression, 12 – Extension, 13 – Left-lateral slip, 14 – Right-lateral slip; the predominant orientation of segments in mechanism corresponds to a displacement direction), 15 – The magnitude scale of earthquake epicenters by CMT, 16 – The magnitude scale of earthquake epicenters, for which CMT2019 data are absent (according to NEIC seismological data). Thin lines with dark-blue circles correspond to tectonic stress axis's [9]. Green color fields, divided by isohypsis, show volumes of seismic energy releasing. Increasing color intensity corresponds to increasing energy volume on 101 J or 10−1 J. the minimal value is 10−7J, the maximal – 1014J. The black numerals in the scheme correspond to energy volume values in joules. Dotes with red figures near them correspond to values of the heat flow in*  μ*W/m−2. The total extensions of studied blocks see in the Figure 6. The authors of the chapter constructed this scheme as all others.*

The geodynamic and seismicity data analysis allow supposing future earthquakes intensity within the Altai OSC area. Events with M7–8 are possible in the west quarter of this area within the Mountain Altai at the left bank of the Argug River, which is the Biya River left source, southwest from the Belyashi settlement. The hypocenters' predominant depth is there about 10-20 km that allows waiting mainly destructive events in this part of the area. Earthquakes with M5–6 are more probable in future within the rest territory of the OSC area.
