Boundaries of the Amurian Plate identified using multiple geophysical methods

Abstract

One of the most topical issues regarding the recent geodynamics of Eastern Asia is identifying the boundaries of the Amurian (AM) block, it has great significance to research the relationship between the Northeast Asia and the Pacific Plate. In this study, continuous Global Positioning System (GPS) measurement data from Northeast China, Southeast Russia, the Korean Peninsula (KP) and Eastern Mongolia are used to calculate the velocity field and Euler pole. The results show that the two sides of the Tanlu fault zone have different velocity directions and Euler centers. And the movement velocity and rotation velocity of the two blocks are different. Chi-square (χ2) statistics indicate significant relative movement between the AM and KP blocks, confirming that they are generally independent and do not belong to the same block. The focal mechanism solutions and energy release indicate that Tanlu fault zone is a large dextral strike-slip fault, there are many deep-focus earthquakes, shallow-focus earthquakes and volcanic earthquakes in this fault zone, which release a lot of energy. Under the strong pushing of the Pacific plate, the KP block is forced to changed direction from SEE to SE along the Tanlu fault zone. These comprehensive calculations show that the AM and KP blocks are two mutually independent blocks, the boundary between them is the Tanlu fault zone.