Metamorphic core complexes (hereafter MCC) revealed in the Transbaikalia have similar features of their patterns. Three levels can be distinguished by structural­material indicators: core, zone of mylonites (dynamically metamorphosed rocks) and overlying formations. The cores are composed of the Paleozoic granites and granitogneisses. Zones of mylonites skirt the cores and are characterized by various tectonites which are formed at the expense of the core rocks. The overlying formations include volcanogenic­sedimentary series of the Mesozoic and the Upper Palaeozoic. The rocks are not metamorphosed, yet subject to brittle deformations. Structurally, they are detached and deposited above the zone of mylonites.

In Transbaikalia, MCC are characterized by synmetamorphic structural paragenesises of one type: low­angle schistosity, micro­ and macro­structures (folds, mineral streaking, boudinage, pressure shadows, C–S structure, kick­bends). According to the kinematic analyses, they were formed by the simple shear mechanism along the zones of deeply penetrating regional dislocations which plunged in the south­eastward direction. Tectonic transportation of the materials developed in the same direction, i.e. the top parts of tectono­stratigraphic sections were displaced against the lower parts in the south­eastward direction. Extension deformations tended in the north­west – south­east direction. Such movements facilitated formation of synthetic listric normal faults and rift basins. The most intensive tectonic exposure period is determined as 112–123 mln years, while the period of metamorphism is assessed as 140–130 mln years. The rocks in depth of the deep dislocation were transformed in conditions of amphibole facies of metamorphism (Т=590–640 °С; Р=3.2–4.6 kbar).

According to our structural-­geological, petrological and isotopic data, the age of the majority of the metamorphic formations of the Transbaikalia is determined as the Late Mesozoic. They were formed in the extension regime due collapse of the Late Mesozoic orogeny, that was caused by accretion­collision events during the Early Mesozoic. Thickening of the continental crust contributed to increase of heat flow and higher plasticity at the crustal bottom. The orogen was thus unstable and flowing and caused regional extension and dislocations at the middle­crust level. Thinning of the crust was accompanied by isostatic uplifting which facilitated emergence of the structural metamorphic complexes of the middle­crust levels on the surface and formation of the metamorphic core complexes.

The subject of comprehensive studies is the underground hydrosphere of the upper crust of the western shoulder of the Baikal rift, being characterized by high tectonic activity in the recent stage of tectogenesis. The studies were focused on the Bayandai – Krestovsky Cape site, considering it as a benchmark for the territory of the Western Pribiakalie (Fig. 1). The available hydrogeological survey database is used to study underground waters circulating at depth of several kilometers. Analyses of deeper waters are conducted on the basis of geophysical data.

According to results of initial geological and geophysical studies [Семинский и др., 2010], the crust at the junction of the Siberian crater and the SayanBaikal folded belt is characterized by a hierarchic zoneblock structure (Fig. 2). Regardless of the scale of studies, the territory under study can be divided into sections of two types, that alternate from NW to SE and represent wide highly destructed zones and relatively monolithic blocks of the crust. The Obruchev fault system is distinguished as the main interblock zone (the 2^nd hierarchic level in the study area). It represents the 50 km long NW shoulder of the Baikal rift (the^1st hierarchic level) and includes the Morskaya, Primorskaya and Prikhrebtovaya interplate zones (the ^3rd hierarchic level). These zones are traced from depth of dozens of kilometers; at the surface, they are represented by fault structures of the highest hierarchic levels.

Specific features of the current zoneblock divisibility of the crust serve as the structural basis for interpreting the materials obtained by hydrogeological studies conducted on the Bayandai – Krestovsky Cape site to research the distribution, mineralization and macrocomponent compositions of waters which represent the subsurface part of the underground lithosphere in the study area. The research is based on analyses of the underground water samples from 46 observation points scattered within the study area. The available amount of sample data can actually be considered as a complete base of standard hydrogeological data for the study area.

The known specific features of hydrogeology of the Western Pribaikalie are confirmed by the general analysis of the available data. In general, fresh waters of subsurface origin of the midand submontane regions are dominant. In the anionic composition of the waters, hydrocarbon ion is predominant. Calcium and magnesium are abundant among basis ions, while potassium and sodium are rare. With the detail data on the Bayandai – Krestovsky Cape site, the above conclusions are more precisely determined, and it is generally concluded that the structural tectonic factor controls the hydrogeology of the region.

The analysis of mineralization, composition, temperature and other characteristics of the underground waters (Fig. 3–6) show that at the low hierarchic level the NW boundary of the Obruchev interblock zone performs a function of a distinct hydrogeological barrier which represents the marginal suture of the Siberian platform. The marginal suture is active at the currently stage of tectogenesis. It separates lowmineralized and fresh waters of the platform block from fresh and ultrafresh waters of the mountainous area. The Predbaikalskaya, Prikhrebtovaya, Primorskaya and Morskaya interplate zones are distinguished within the limits of these structures. At the given hierarchic level, they control the positions of the corresponding anomalies in terms of water exchange modes, general mineralization and water cut ratios. The magnetotelluric sounding data (Fig. 2 and 7) suggest that the anomalies are subsurface manifestations of deep sections of conductivity; such sections have fluid origin in the region under study. Specific features of the structure of such anomalies are controlled by the presence of interblock zones of the fault level of the hierarchy. The interblock zones are composed of tectonic dislocations of various ranks. Depending on their specific internal structures, such dislocations can act as impermeable screens or channels for migration of fluids.

Based on the joint interpretation of the results of the hydrogeological studies and the earlier geological and geophysical studies on the Bayandai – Krestovsky Cape site, a conceptual model showing specific features of fluid saturation of the upper crust of the western shoulder of the Baikal rift is developed (Fig. 8). Generally speaking, the underground hydrosphere of the Western Pribaikalie is a uniform system at the subsurface and deeper levels, and its structure and content are mainly determined by the active zoneblock structure of the crust in the region under study. Its nature is controlled by the development of the Baikal rift, which western shoulder (and also the adjacent platform region) is occupied by a hierarchy of subvertical zones in the upper crust that are anomalous in terms of permeability concerning underground waters. In the tectonically active segment of the region, these zones are larger than the blocks and thus cause more significant dislocations and higher watercut of the crust. The relationship between dislocations and watercut allows determining specific features of the zoneblock structure by regions by applying methods of hydrogeological surveys for studies of shallow horizons and geophysical methods, which are more sensitive to fluid contents, for studies of deeper layers. On the other side, geophysical and hydrogeological data (at least on tectonically active regions) should be interpreted with account to the concept that the fields under study depend on the structural status of the rock massif, rather than on the lithology.

The publication presents a review of the structure and seismotectonic features of the Pacific margin of the NorthEastern Honshu Island on the basis of data from seismic reflection and CDP, drilling and detailed seismic studies in view of the megaearthquake (M_w=9.0) which occurred in Japan on March 11, 2011. The megaearthquake is discussed in terms of its position in the succession of the strongest events (M≥7.6) in the area under study within the historical period and in the recent timeline. It is suggested that the period of recurrence is about 40 years for great events and about 1000+ years for megaearthquakes. A number of facts suggesting a probability of a planetaryscale earthquake in the Honshu Island region are revealed. Specifically, a seismic gap with a total length of about 800 km is determined in the study area. It is located southward of 39° north latitude has already manifested aftershocks of the megaearthquake of March 11, 2011. It is probable that the megaearthquake was related to the deep thrust along the Benioff zone and the Oyashio nappe being its structural cap rock in the middle Pacific slope. The sequence of its aftershocks is compared with those of the SumatraAndaman (Mw=9.3, 2004) and Simushir (Mw=8.3, 2006) earthquakes. It is established that development of the aftershock sequences of the first and second events was very similar in time, and development of the areas of aftershock epicentres of the first and third earthquakes is similar in space. The above similarities give grounds to suggest that an aftershock (M~8.0) is possible with a relative shifting from the main shock towards the deep trench.

 It is suggested that the eruption of the Sarycheva Peak volcano on 11 June 2009 may have been related to strong earthquakes which occurred in the Middle Kuril Islands from 2006 through 2009 (Figure 1), geodynamic processes (such as tectonic activation, subduction, and friction of contacting blocks), tectonic stresses, melting of rocks, rising of the melting substance, gases and fluids.

The publication discusses the earthquake hypocenters profile along the Kuril Islands (Figure 2), the seismogeological depth profile of volcanoes of the Kuril Islands that was published by T.K. Zlobin (Figure 3), and positions of the magmatic chamber and the seismogenic zone of the SenHelens volcano from the publication by S. Carey (Figure 4).

The map of earthquake epicenters for the Middle Kuril Islands is constructed on the basis of the NEIC catalogue (Figure 5). A corresponding depth profile showing earthquake hypocenters is constructed (Figure 6).

An aseismic area is detected underneath the Matua Island (Sarychev Peak volcano); it is almost 30 km wide and about 200 km thick. In the Middle Kuril Islands, magma lifting and eruption were facilitated by stretching of the lithosphere (Figure 7), occurrence and activation of breaks, fractures and faults due to earthquakes which occurred from 2006 though 2009, and lifting of gas and fluids (Figure 8). The eruption was possible by explosion upon instant injection of fluids into the porous space due to considerable shear stresses, which occurred after the earthquakes, and the reaction of dehydration. It can also result from supply of volcanic gases and fluids, according to the vacuumexplosion fluid dynamics model.

The publication presents a review of alterations of stagnant elements of the Baikal region that occurred during formation and development of the Baikal rift from the Late Cretaceous. Nowadays the natural complex contains the elements varying in age and genesis as they developed during three large stages. In the course of the regional evolution, peneplains altered into uplifted platoes, alpinetype and goltsy mountain ranges; humid quasitropics and subtropics developed into arid zones with the Mediterraneantype climate and moderate and nival zones which were subjected to recurrent mountainandvalley glaciations. Water basins became ultradeep and hosted water species populations which are unique in terms of the biodiversity and endemic features. The main stages of environmental alterations were separated by phases of tectonic movement and tectonic inversions. The alterations’ review is based on consecutive series of cartographic representations of the paleogeographic scenarios.

The paper discusses further ways to improve the geodynamic informativity of the hydrogeodeformation field (HGD field) monitoring. New methods for efficient assessment of the stressstrain state of the geological environment and seismic hazard are proposed. There are described the methods of monitoring data processing, distinguishing of HGD cycles, and construction of «forecasting» contours along extremums of these cycles. It is revealed that responses of the HGD field to development of planetaryscale endogenic geodynamic processes of earthquake preparation (with M>7) are simultaneously manifested in all seismically active regions of Russia which are remote from each other. Such responses occur from one to three months prior to such seismic events. The mechanism of this phenomenon can be disputed. The authors support the «planetary pulsation» concept which is up for the most recent debates. As evidenced by the HGD field monitoring data, strong earthquakes are a consequence of this phenomenon.

The article is dedicated to the 110th anniversary of E.V. Pavlovsky, an eminent geologist in the second half of the 20th century and a leading researcher of East Siberia. He discovered the Baikaltype through system in the Sayano-Stanovoe dome uplift. He authored a new theory of arc genesis and revealed a number of general regularities in development of the Earth's crust.