Обсуждается проблема современной геодинамики Дальневосточного региона на основе мониторинга разномасштабных деформаций и сейсмичности в области сочленения Евразийской, Североамериканской, Тихоокеанской, Амурской и Охотской литосферных плит с применением современных методов космической геодезии и широкополосной сейсмологии. Дан краткий обзор этапов развития Единой сети геодинамических наблюдений ДВО РАН, основных результатов сейсмологических и GPS/ГЛОНАСС-наблюдений, полученных в рамках целевой комплексной программы научных исследований ДВО РАН «Современная геодинамика, активные геоструктуры и природные опасности Дальнего Востока России (2009–2013 гг.)» и проектов ДВО РАН 2014, 2018, 2019 гг., а также достигнутых позиций ДВО РАН в области геодинамики. The problem of the recent geodynamics of the Far East region is discussed based on monitoring of different-scale deformations and seismicity in the articulation of Eurasian, North American, Pacific, Amurian and Okhotsk lithospheric plates using modern methods of space geodesy and broadband seismology. We present a brief overview of the development stages of the Unified Network of Geodynamic Observations of the Far Eastern Branch of the Russian Academy of Sciences, the main results of seismological and GPS/GLONASS observations obtained within the framework of the Targeted Comprehensive Research Program of the Far Eastern Branch of the Russian Academy of Sciences for 2009–2013 «Recent geodynamics, active geological structures and natural hazards of the Far East of Russia», Projects of the Far Eastern Branch of the Russian Academy of Sciences (2014, 2018, 2019) and the achievements of FEB RAS in the field of geodynamics.

ХАРАКТЕР ДЕФОРМАЦИОННЫХ ПРОЦЕССОВ В ЗЕМНОЙ КОРЕ ВЕРХНЕГО ПРИАМУРЬЯ

РАЗВИТИЕ ГЕОДИНАМИЧЕСКОЙ СЕТИ НАБЛЮДЕНИЙ НА ТЕРРИТОРИИ ВЕРХНЕГО ПРИАМУРЬЯМ.А.Серов, В.С.Жижерин Институт геологии и природопользования ДВО

Based on the published GPS data for the Upper Amur region, the parameters of the tensor of strain rates are calculated. In particular, we obtain such parameters of the main rates and main directions of strains, maximum shear strain rates and its directions, dilatancy rate, and second invariant of the strain rate tensor. The obtained results indicate a high tectonic activity in the zone of interaction between the Eurasian and Amurian plates and Stanovoy geoblock. The zones of high-rate aseismic displacements are revealed. It is supposed that NE-trending faults will be activated at the contemporary stage at the boundary between the Eurasian and Amurian plates.

This paper reports the first data on present-day movements in the northern margin of the Argun Continental Massif, obtained on the basis of GPS measurements. The processed GPS data have been obtained to calculate the vector field of displacement velocities in the geodynamic survey site of the Upper Amur Region. The estimated displacement parameters (direction and magnitude) are indicative of the uniform velocity vector field of the points in the northern margin of the Argun Massif and the absence of considerable motions within its range (differences in the vector components do not exceed a few millimeters per year). A conclusion is made on the present-day kinematic integrity of the northern margin of the Argun Massif.

The first results on current movements are presented for the western part of the Dzhugdzhur–Stanovoi Terrane based on GPS geodesy of a geodynamic survey area of the Upper Amur region. Processing of the GPS data resulted in a vector field of the displacement rates of points of the geodynamic survey area with zones of intense deformations. It was concluded from a comprehensive analysis of geological–geophysical data and estimates of the displacement rates that the terrane is characterized by kinematic integrity and was subjected to a complex of tectonic factors related to the evolution of the eastern segment of Baikal Rift Zone in the area of transpression interaction of the Eurasian and Amur plates.

We present the first data of GPS measurements on recent motions in the east of the Mongol Okhotsk Fold Belt. Processing of GPS data yielded a vector field of the velocities of observation point displacements in the geodynamic network of the Upper Amur region. Comprehensive analysis of geological and geophysical data and the estimated velocities of site displacements in this network have shown kinematic heterogeneity of the present-day Mongol Okhotsk Fold Belt and an intricate deformation pattern there. The tectonic regime within the belt permits considering it a buffer or transit zone, where tectonic stresses arise as a result of the different kinematics of the surrounding tectonic structures. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

We analyze recent crustal movements, based on data of GPS measurements on the Amurian Plate and its margins. Most of the velocities were borrowed from scientific publications. Also, our new and updated data of periodic and permanent GPS observations are presented. A continuous field of strain rates has been constructed using the combined field of movement velocities. Dilatation rates and the directions and values of the main strain axes have been calculated. We have made a quantitative estimation of the maximum shear rates and their directions. Zones of background deformations in the inner part of the Amurian Plate have been revealed along with high-strain zones. Zones with intense tectonic activity, corresponding to areas of reduced lithosphere, often show manifestations of Late Cenozoic volcanism. Part of them can be interpreted as the present-day boundaries of intracontinental geoblocks and small lithospheric plates.

Шестаков Н.В., Ohzono M., Takahashi H., Герасименко М.Д., Быков В.Г., Гордеев Е.И., Чебров В.Н., Титков Н.Н., Сероветников С.С., Василенко Н.Ф., Прытков А.С., Сорокин А.А., Серов М.А., Кондратьев М.Н., Пупатенко В.В.//Доклады Академии наук, 2014

The Okhotsk deep focus earthquake (M (w) = 8.3), the largest in the history of instrumental seismology, occurred on May 24, 2013, at 05:45 UTC in the Sea of Okhotsk near the western coast of the Kamchatka Peninsula. For the first time we have succeeded in catching the field of horizontal and vertical coseismic offsets generated by a strong deep seismic event, and investigating its characteristics using continuous GPS measurements. Based on these data and taking into account the seismological information, we have developed a dislocation model of the Okhotsk deep focus earthquake.

Small coseismic offsets detectable using GPS techniques were found more than 2300 km away from the Great Tohoku 2011 earthquake epicenter. Area of the most intense far-field co- and postseismic deformations with the maximum offset values exceeding 40 and 18 mm, respectively, extends westward from Honshu Island to the Korean Peninsula, northeastern China and southern Far East Russia. Sakhalin Island does not exhibit notable displacements caused by the earthquake, in contrast to the adjacent territories. A rectangular fault model with uniform slip was developed based on the GPS-detected far-field coseismic displacements using the spherically layered Earth assumption. Both far- and near-field coseismic deformations are generally well described by a single-segment rupture of 200 × 96 km2, characterized by thrust slip with minor strike-slip component of about 33 m and by the seismic moment value of 1.9·1022 N·m (Mw = 8.8), which roughly constrains the major slip area. The resultant compact fault geometry revealed that the main portion of the seismic moment had been realized in a relatively small-sized rupture segment. The sensitivity of far-field GPS data to the major slip area might also be used in the development of a seismically generated giant tsunami warning system.

A combining of the methods of the magneto-telluric probing and gas-geochemical investigations was carried out for the first time in the territory of the southern part of the Zeya–Bureya basin to study its deep structure and location of the faults. A gas-electric section was plotted to the depth of 8 km. along the latitudinal profile dissecting the Grodekovo uplift and the Lermontovka depression. Electric characteristics of the sedimentary cover and basement of the basin are obtained. Confinement of the anomalies of soil gases (helium, hydrogen, radon, methane, hydrocarbons) to the reduced zones, serving as channels for a degassing of the Earth’s interior, is established.

Today, one of the most topical questions in the recent geodynamics of eastern Asia is that concerning the existence of the Amurian Plate and its boundaries. An unambiguous answer is difficult to obtain because seismicity is relatively rare and weak and the plate boundaries are often geomorphologically unclear. One of the methods that can help is satellite geodesy. In the present study, the velocity field of recent horizontal crustal movements was obtained from five repeated GPS observations on the Amur–Zeya geodynamic test ground (Amur Region) in 2001–2007. On this basis, the parameters of the relative rotation of the Eurasian and Amurian plates were calculated. The coordinates of their rotation pole were found to be 122.285° E and 58.950° N, and the angular rotation velocity 0.095 deg/Myr. The resulting kinematic model describes the motion of the Eurasian and Amurian Plates as independent tectonic units. According to statistical analysis, this hypothesis is true at a confidence level of more than 99%. Also, calculations have shown that the eastern boundary of the Amurian Plate passes through a branch of the Tan-Lu fault system. The kinematic model for the Eurasian and Amurian Plates agrees well with data on the kinematics of active faults and the modern tectonic stress field at the plate boundary.

The results of long-term studies of the neotectonic processes and related phenomena such as the Earth's interior degassing, the fluid discharge, and the high seismicity in the zone of interaction between the Amur and Okhotsk lithospheric plates at the transition between the Verkhnii and Srednii Amur regions were used for defining the separate structural blocks with different geodynamics and analyzing their relations with the seismic events during the periods of high seismic activity and quiescence. The heliometric and atmochemical studies in the Zeya-Bureya basin revealed zones of high permeability. Long-term observations of the fluid dynamics at the Konstantinovka mineral water deposit demonstrate a correlation between the variations in the water-soluble helium contents and the changes in the stress-deformed state of the blocks located up to 200 km away from regime observation sites.