High-Precision Vertical Deformation of the Chinese Mainland Constrained by Leveling and GNSS data

Abstract

Summary A high-precision and high-resolution vertical velocity for the Chinese mainland is obtained by integrating precise leveling and GNSS data, using a Helmert joint adjustment method. The results show that the surface vertical rates range between -3.0 and 3.9 mm/yr with continuous deformation in most areas, except the obvious subsidence at the rates of -15.0 to -94.2 mm/yr induced by groundwater exploitation in the North China Plain. Particularly, the central and southern Tibet, Tien Shan, Alashan, Ordos, eastern Cathaysia, and Northeast China uplift at the rates of 0.5 – 3.9 mm/yr; the southeastern Tibetan Plateau, Sichuan basin, and Yangtze block are dominated by surface subsidence at the rates of -3.3 to -0.5 mm/yr. Furthermore, the vertical rates vary little between the eastern and western regions of the Chinese mainland despite their pronounced differences in horizontal deformations. The effects of gravity isostasy and non-tectonic factors, including the environmental mass loads, Glacier Isostatic Adjustment (GIA), poroelastic expansion/compression, and mining operations have partially contributed to the vertical deformation of the Chinese mainland. Overall, this velocity reflects the complicated deformation features induced by the multiple geodynamic processes of the Chinese mainland. These geodynamic processes include isostasy, orogenic processes, and geothermal anomalies associated with slab subduction/plate collision.