Combining Application of TOPS and ScanSAR InSAR in Large-Scale Geohazards Identification

Objectives  InSAR technique has the ability to detect small deformation of the earth's surface. However, it is still a great challenge to identify the potential geohazards using InSAR in wide area. How to obtain reliable InSAR products in "large-scale, fast and economic" is still the key work of general survey for geohazards identification. Methods  Sentinel-1 TOPS and ALOS-2 ScanSAR data have large-wide swaths of hundreds of kilometers. Therefore, range split spectrum, Stacking-InSAR and other technologies are comprehensively used to identify geohazards using Sentinel-1 TOPS and ALOS-2 ScanSAR data in the Jinsha River area from Panzhihua City to Wudongde hydropower station. Firstly, sub-swath images of ScanSAR are processed with each other by differential interferometry, and range split spectrum method is used to estimate and compensate ionospheric delay for SAR interferometry.Then, TOPS full swath ima- ges are processed with perpendicular and temporal baselines of less than 200 m and 60 d, respectively. Finally, linear deformation rates of TOPS and ScanSAR data are estimated using Stacking-InSAR technique. Results  Forty-six potential geohazards are identified using Sentinel-1 TOPS data (January 2018 to January 2019), and ALOS-2 ScanSAR data (February 2017 to February 2020) have identified forty-four potential geohazards. Field investigations show that there are almost deformation phenomena in the location of identified geohazards by InSAR. Conclusions  The combined applications of TOPS and ScanSAR modes can fully grasp the situation of geological hazards as far as possible.