**5. The OSC area in the Baikal system and northwest Transbaikalia**

The OSC area includes territory between NEP and the Amurian Block (or the small plate in other interpretation [18]) within the Baikal Rift System and its northeast continuation (**Figure 4**). The area length is 950 km, its width – 11-230 km and the total releasing energy volume reaches 1.79362·1015J. Normal northeast faults predominate there with the left-lateral slip component. Tectonic stress axis's have stead northeast direction. The releasing energy level oscillates from 104 to 1012J, M changes from 3 to 6 reaching 6–7 for some certain events. The zone of active extension stands out within all Baikal Rift System after mechanism earthquake solutions. Releasing energy maximal volumes coincides with this zone. The extension processes do not get out from the crust (10-33 km) according to analysis of the hypocenters development after CMT2017 data. Separate faults in adjacent parts of the Amurian Block are left-lateral slips, rarely thrusts to southwest.

Normal faults and left-lateral slips with extension component prevail near southwest ending the Baikal Rift System at the depth of 10-16 km within the interblock zone dividing NEP and the Amurian Block. Yu. Gatinsky and G. Vladova together with V. San'kov discovered during 2008 field itineraries in the Barguzin Depression distinct changing slips, causing seismic dislocations, by later normal faults [5]. These faults cross from the Paleozoic granite to the yang alluvium corresponding to the time progress of the transtension process. The maximal increasing the seismic energy dissipation up to 1.4·1015J occurs above normal faults restricting the Baikal Trough in southwest [1]. Just there near the Kultuk settlement the earthquake with M6.3 took place in 2008. The earthquake near destroyed the settlement and some communication ways. West we observed the displacement of modern streamlets' thalwegs along NW slips with amplitudes up to 10 m. NEP displaces on 105.6° SE with the velocity 25.9 mm/y according to measuring in the Irkutsk Station into absolute coordinates of ITRF2014. Vectors within the Amurian Block have azimuths of 106.9° -108.0° SE on the Ulan-Bator Station with the velocity 31.2 mm/y and up to 121° SE and more on some Chinese stations with velocities 26-35 mm/y. HF values reach 96-140 μW/m−2 in the Lake Baikal Trough in comparison with 36–79 at its sides within NEP and the Amurian Block.

Note, that in the east part of Central Asia horizontal displacements predominate into transtension conditions with opening numerous rifts in the Baikal System,

#### **Figure 4.**

*The OSC area within the Lake Baikal and northwest Transbaikalia takes place in seismic active zones separating NEP and the Amurian block. See summary legend for the Figure 1.*

**9**

**Figure 5.**

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

around the Ordos Block and in boundaries of some other blocks. The development of those extension processes has different interpretation: squeezing out east some blocks including the Amurian Block under the influence of the Hindustan – Asia collision [12], or the upper mantle flow generated by the deep submergence of the Pacific slab under Asia [19–21]; mantle plume raising under north Mongolia and the Baikal region (see **Figure 3**) resulted in the crust extension and rift formation [7, 17]. The increase anisotropy exists in the majority regions of central Asia with coinciding north-northeast direction of splitting *Pn*-waves high velocities with the axes of maximal compression and GPS vectors [22], that shows the complete deformation coupling within crust and lithosphere mantle. The authors of paper [23] arrived at the same conclusion for the region of Baikal, west and central Mongolia. Data on geodynamics and seismicity of the regarded OSC area allow predicting maximal intensive seismic events with M up to 7–9 within northwest third of the area territory: to the north in the Stanovoi Upland at both banks of the Upper Angara River and farther south east of the Lake Baikal in the north part of the Barguzin Range. New earthquakes with M up to 6–7 can be in the other part of the OSC area. The main hypocenters concentrations of preceding events were at the depth 10-16 km, so within regarded area disastrous earthquakes will be the most probably,

The area situates in the territory of Zabaikalian Krai, south Yakutsk, and northwest of the Amurian District between the Vitim River and upper stream of the Aldan River (**Figure 5**). Its length is 464 km, width – 64-108 km, and the total seismic energy reaches 4.64153·1016J, that is nearly equally to the energy of the OSC area of the north Pamir - 4.50343·1016J [24]. The energy level oscillates on the regarded

events reaches 6–7. Northeast normal faults with the left-lateral slip component predominate in the west of the OSC area and northwest left-lateral slips develop in

*The OSC area in northeast Transbaikalia settles down within the seismic active interblock zone between NEP* 

*and the Amurian block. See summary legend for the Figure 1.*

the east. Tectonic stress axis's have the stead northeast direction.


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

most likely as near Kultuk in 2008.

area between 104

**6. The OSC area in the northeast Transbaikalia**

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

around the Ordos Block and in boundaries of some other blocks. The development of those extension processes has different interpretation: squeezing out east some blocks including the Amurian Block under the influence of the Hindustan – Asia collision [12], or the upper mantle flow generated by the deep submergence of the Pacific slab under Asia [19–21]; mantle plume raising under north Mongolia and the Baikal region (see **Figure 3**) resulted in the crust extension and rift formation [7, 17]. The increase anisotropy exists in the majority regions of central Asia with coinciding north-northeast direction of splitting *Pn*-waves high velocities with the axes of maximal compression and GPS vectors [22], that shows the complete deformation coupling within crust and lithosphere mantle. The authors of paper [23] arrived at the same conclusion for the region of Baikal, west and central Mongolia.

Data on geodynamics and seismicity of the regarded OSC area allow predicting maximal intensive seismic events with M up to 7–9 within northwest third of the area territory: to the north in the Stanovoi Upland at both banks of the Upper Angara River and farther south east of the Lake Baikal in the north part of the Barguzin Range. New earthquakes with M up to 6–7 can be in the other part of the OSC area. The main hypocenters concentrations of preceding events were at the depth 10-16 km, so within regarded area disastrous earthquakes will be the most probably, most likely as near Kultuk in 2008.
