GPS geodetic constraints on the kinematics of the Amurian Plate

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.