RESEARCH ON THE CHARACTERISTICS OF PRESENT CRUSTAL DEFORMATION IN BEIJING AREA BASED ON GNSS

Abstract. We use the GAMIT/GLOBK software to process more than 100 GNSS sites observation covering the Beijing area from 1999–2021 to obtain the three-dimensional velocity field of present-day crustal movement, and the deformation and strain characteristics of Beijing were calculated and comprehensively analyzed by combining with historical earthquakes. The results show that: 1) The present-day horizontal crustal motion of Beijing is dominated by the SEE direction with a rate of 5-10 mm/a with relative to the stable Eurasian reference frame, and the northern and southern areas show uplift as a whole with a rate of 1–3 mm/a, while the central plain area shows overall subsidence, with a maximum subsidence rate of about 130 mm/a. 2) The horizontal deformation is mainly N-E/N-W extension, accompanied by weak shear activity. 3) The N-W trending faults show sinistral strike slip movement as a whole, with about 1.1–2.0 mm/a, and N-E trending faults show dextral strike slip with a rate of less than 1 mm/a. 4) The historical large earthquakes are distributed within the positive and negative gradient zones of the first shear strain rate, transition zones of the rotation rate, and are mostly distributed at the edges of the high and low value zones of the second shear strain rate, and the edges of the high value zones of the east-west strain rate also have a background of large earthquakes.