Construction method of GNSS multi-scale crustal movement field considering robust estimation

Accurate acquisition of strain rate field is an important part in seismic risk analysis by using GNSS observations, while the key point of this work is to build an accurate crustal deformation field model. In this paper, we propose a construction method of multi-scale crustal deformation field considering robust estimation based on traditional one. Considering the influence of non-tectonic deformation caused by poor observations and bad observational environment, we extract an accurate crustal deformation model. Through the simulation analysis of adding artificial gross error in the actual observations, it is verified that this method has good robustness. We calculate the latest GNSS observations and obtain an updated crustal deformation map in Sichuan and Yunnan regions. From the new GNSS velocity field, the robust iterative algorithm detects 20% weight reduction stations and 2% weight removal stations. The observation piers of weight reduction and weight removal stations are all built on the soil layer, and the formal error of velocity is large, which indicates there is obvious local non-tectonic deformation in these stations. If we adopt the equal weight strategy to calculate the strain rate field, it will inevitably produce significant gross errors in the calculated strain rate field, which will affect the following important work of earthquake trend determination or risk analysis.