Monitoring Of Landslide Deformation Based On InSAR

China is a country with complex geological environment.It is seriously affected by geological disasters.The terrain in the southwest mountainous areas is complex,and the ravines and mountains overlap.The task of monitoring is so difficult,that the traditional landslide investigation and monitoring cannot be practical.A large landslide occurred on June 24,2017,in Xinmo village,Diexi town,Mao county,Sichuan province.The landslide was located in the Longmenshan fault zone.Due to the large height difference,it was a typical high-level geological landslide with destructive force.The Xinmo village was buried entirely,and eighty-three persons lost their lives in the landslide disaster.Thus,the monitoring of landslide is of utmost significance.Interferometric synthetic aperture radar(InSAR)is an effective method to detect the surface deformation with high accuracy,low cost and high efficiency.In order to investigate the effectiveness of time-series radar differential interferometry for the monitoring of mountain landslide,we took the landslide of Xinmo village,Mao county as an example.The high-resolution ascending orbit SAR image from Sentinel-1A was selected as the data to calculate the deformation rate of Xinmo village.The reliability of the monitoring results was validated with the unmanned aerial vehicle image,and the factors of landslide were discussed.Our research tasks and results are listed below.(1)We used the permanent scatterer interferometry synthetic aperture radar(PS-InSAR)method to study the deformation of Xinmo village,and thirty-five Sentinel-1A scenes were utilised to obtain the deformation information of the study area.The results based on PS-InSAR showed that the rate of deformation points in the study area was between-50 mm/a and 20 mm/a.(2)Due to the special geographical location of the study area and the large amount of vegetation,in order to demonstrate the effectiveness of InSAR,we used another small baseline subset interferometric synthetic aperture radar(SBAS-InSAR)method to study the deformation of the study area.By reducing the values of time base and space baseline,more interference pairs were added,and the time-series deformation information of the study area was modeled.The results based on SBAS-InSAR showed that the rate of deformation points in the study area was between-30mm/a and 10mm/a.(3)We compared the results derived from the two methods,and analyzed the deformation range,deformation level,and the spatial distribution of the monitoring results.The results showed that the deformation rate at the same points for the two methods increased obviously before the landslide occurred,and the deformation rate was small for the points away from the ridge.Few deformation points occurred in the debris flow area with vegetation.The results indicated the reliability of InSAR for monitoring the landslide of the Xinmo village.(4)Finally,the possible causes of the landslide deformation were preliminarily discussed.Our results showed that the change of rainfall and rate of deformation were kept consistently.The factors including the geological conditions,and historical seismic disaster were also discussed.The landslide could be induced by the rainfall,geological conditions,and historical seismic disaster.