GNSS Observations of Crustal Deforamtion: A Case Study in East Asia

Abstract

The East Asia is located in a complex convergent region with several plates, e.g., Pacific, North American, Eurasian, and Philippine Sea plates. Subduction of the Philippine Sea and Pacific plates and expulsion of Eurasian plate with Indian plate collision [22, 36, 15, 18, 11] make the East Asia as one of the most active seismic and deforming regions (Fig. 1). Current deformation in East Asia is distributed over a broad area extending from the Tibet in the south to the Baikal Rift zone in the north and the Kuril-Japan trench in the east, with some ambiguous blocks, such as South China (Yangtze), Ordos and North China blocks, and pos‐ sibly the Amurian plate, embedded in the deforming zone. The inter-plate deformation and interaction between the blocks are very complicated an active, such as the 1978 Mw=7.8 Tangshan earthquake located between North China and Amurian blocks. Since the 1960s when the theory and models of seafloor spreading and plate tectonics were established, the large Eurasian plate has been considered as an independent rigid plate, such as RM2, P071 and NNR-NUVEL1A [6], and even the present-day global plate motion models of ITRF se‐ quences based on the space geodetic data [10]. In fact, East Asia is very complicated defor‐ mation zone with several possible rigid blocks [22]. [36] proposed that East Asia consists of several micro-plates. However, because of low seismicity and there being no clear geograph‐ ical boundary except for the Kuril-Japan trench and the Baikal rift zone, it is difficult to accu‐ rately determine the geometry and boundary of sub-plates in these areas. The borderlines of the micro-plates are not visible, especially in the complicated geological tectonic regions in North China far away from the Qinghai-Tibet plateau, and convergent belts of Eurasia, North America and the Pacific plate. Therefore, it is difficult to confirm the tectonic features and evolution of the deformation belts in East Asia.