No abstract

No abstract

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.

International audienc

Based on multiyear measurements of present-day motions in the central area of the Baikal rift system, new data on the kinematics of horizontal motions, relative horizontal deformation rates, and rotation velocities in the area of junction of the South Baikal, North Baikal, and Barguzin rift basins have been obtained. This area is an intricate structure with two transfer zones: Ol’khon–Svyatoi Nos and Ust’-Barguzin. It is shown that crustal blocks are moving southeastward, normally to the structures of transfer zones and at an acute angle to the Baikal Rift strike, which corresponds to the right-lateral strike-slip extensional faulting along the major structure. The average horizontal velocities increase from 3.0 mm yr–1 in the northern South Baikal basin to 6.5 mm yr–1 in the Barguzin basin. The elongation axes prevailing in the study region are mainly of NW–SE direction. The areas of intense deformations are confined to structures with high seismic activity in the South Baikal and, partly, Barguzin basins. This confirms the existence of a present-day zone of the Earth’s crust destruction in the Baikal rift system, which is the most likely source of strong earthquakes in the future. Two zones with rotations in opposite directions are recognized in the rotation velocity field. Clockwise rotation is typical of structures of N–NE strike (Maloe More basin, southern North Baikal basin, Barguzin Ridge rise). Counterclockwise rotation is determined for NE-striking structures (northern South Baikal basin, southern Barguzin basin). In general, the obtained data show an intricate pattern of present-day horizontal dislocations and deformations in the area of junction of NE- and N–NE-striking rift structures. This suggests left- and right-lateral strike-slip faults, respectively, within them.