An uncertainty-weighted fusion method of PS-InSAR, GNSS, and leveling for millimeter-level deformation monitoring in sensitive observatory environments

• Uncertainty–weighted multi–sensor fusion monitors mm–level settlement. • Unified vertical reference achieves ± 0.5 mm cross–technique precision. • 3D irregular load model attributes > 90% settlement to construction. • Workflow separates construction and tectonic deformation signals. Achieving millimeter-level measurement accuracy at high-sensitivity seismic observation stations is extremely challenging, especially when urban engineering construction is carried out in their vicinity, causing non-tectonic ground deformation. Such complex environments expose the limitations of traditional multi-sensor deformation monitoring methods, which are specifically manifested in insufficient precision calibration, lack of registration of a unified reference framework, and insufficient in-depth analysis of the attribution of mechanical mechanisms. These problems restrict the reliable separation of deformation signals caused by tectonic and non-tectonic causes. In response to the above problems, this study proposes a multi-sensor fusion framework based on uncertainty weighting. The framework integrates three observation methods, namely Permanent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR), Global Navigation Satellite System (GNSS), and high-precision leveling, and combines the three-dimensional irregular load model to carry out the attribution analysis of the deformation mechanism. The results show that in the application practice of the Jinzhou seismic station from 2021 to 2024, the framework controls the deviation of results between different monitoring technologies within ± 0.5 mm, clarifies that more than 90% of the peak settlement is caused by engineering construction activities, and realizes the effective separation of deformation signals caused by tectonic and non-tectonic causes.