Research on the method of pure deformation field by GNSS and InSAR

Abstract

This paper takes the geological disaster-prone area of Mayang County of Hunan Province as the test area.The results of the GNSS station time series calculation show that the vertical shape variable of the regional overall crustal plate ranges from 3.39mm to 4.85mm, indicating the overall upward trend;According to the calculation based on the InSAR long time series, the absolute vertical shape variable of the whole surface ranges from -41mm to 31mm, indicating the overall subsidence and local uplift trend.This paper explains the difference between the two methods and the reasons for the difference.It determines the difference is the difference between the bedrock plate movement and the bare surface absolute movement and forms a set of regional pure deformation field calculation methods. In the study area, the GNSS bedrock observation and InSAR surface observation results were respectively fitted with the global spatial difference. Then the difference was calculated to obtain the relative shape variable of the exposed surface movement compared with the bedrock, and the regional pure settlement field was -34.46mm~34.89mm. In this paper, it is proved by experiments that there are significant differences between the monitoring results of bedrock GNSS station and InSAR technology in the geological disaster research area. If the absolute surface shape variable observed by the InSAR method is not deducted from the relative shape variable, it is easy to misjudge the landslide hidden danger trend. To better reflect the surface subsidence trend, when studying the subsidence of geological disaster areas, it is necessary to subtract the bedrock shape variable from the analysis and to use the surface’s movement trend (pure deformation field) relative to the crustal bedrock as a variable.