Application Of InSAR Technology In Surface Deformation Monitoring

In recent years,the geological disasters caused by surface deformation have caused huge losses to people's normal production and life.Therefore,the surface deformation caused by nature or man is receiving people's attention year by year,and it is urgent to monitor the surface deformation efficiently.Surface deformation includes deformation caused by crust activity represented by earthquakes,urban land subsidence caused by artificially over-exploiting groundwater or massive construction of infrastructure,and ground subsidence caused by mining of underground mineral deposits.Synthetic Aperture Radar Interferometry(InSAR)technology developed in recent years has made up for the shortcomings of traditional leveling and GPS measurement,such as high investment,long time-consuming and low efficiency.It can observe a wide range of deformation zones without weather restrictions.In this paper,InSAR technology is used to study the problems of seismic deformation,urban land subsidence and ground subsidence in mining areas.The main research results are listed as follows:(1)Explain InSAR method in detail,including D-InSAR,MAI and SBAS-InSAR.Introduce the theoretical parameters related to seismic research and the Okada dislocation model.And explain several SAR data used in the study.(2)Taking the earthquake in Iraq on November 13,2017 as an example,use Sentinel-1 data to analyze the seismic deformation.Use D-InSAR to obtain the earthquake deformation of LOS.Use MAI to obtain the earthquake deformation of the azimuth direction.Then use mathematical method to calculate the earthquake deformation values in the east-west,north-south and up-down directions.Calculate the earthquake source parameters based on the Okada model.The result turns out that the Iraq earthquake is mainly thrust tectonic quake,and the fault is expanding along the northwest.The lower plane in the northeast has declined,and the upper plane in the southwest has risen.Finally,compare the results with the results of research institutions such as USGS,and prove that the results are reliable.'(3)In the study of urban land subsidence in Wuxi,26 C-band ASAR satellite images from May 2004 to April 2010,22 L-band ALOS satellite images firom February 2007 to February 2011 and 7 X-band COSMO satellite images from July 2011 to July 2012 was used to acquire urban land subsidence result in Wuxi area,and obtain the time series deformation result by SBAS-InSAR technology.Studies have shown that due to excessive exploitation of deep groundwater,severe subsidence phenomenon has occurred in the Xixi-Chengnan area.After the announcement of policy that prohibit groundwater exploitation in Jiangsu Province,a small-scale rebound occurred in the Xishan District and the Xinwu District.Finally,compare the results of ASAR and ALOS.It turns out that R2 is 0.5568,p<0.001<0.05,and pass the significance test of 0.05 level.In addition,compare level data and results of the ASAR to analyze the accuracy of the ASAR results.And it turns out that the InSAR results are in good agreement with the level observation results.(4)In the study of the ground subsidence in Juye Coalfield,obtain 21 C-band Sentinel-IA satellite images from May 2017 to November 2018,and calculate the deformation of Juye Coalfield by SBAS-InSAR technology.Generate the time series deformation result of the seven major mining areas.The results show that during the one-and-a-half-year study period,significant sedimentation occurs in the mining area,especially in the area centered on the Guotun mining area,with a cumulative settlement of-72 mm.And during the study period,69%of the land had a settlement of more than 45 mm.Finally,taking the Guotun mining area as an example,compare level data and SAR results to analyze the accuracy of SAR results.And the results obtained by two techniques are found to be highly correlated.(5)It can be concluded from the above three applications that InSAR technology can be maturely applied to surface deformation monitoring.D-InSAR is not limited by bad weather and time,and acquires the deformation value under a large area with high precision.However,it is easy to generate errors such as time-space loss coherence and atmospheric delay in the monitoring of long-term micro-deformation,which affects the monitoring results.Therefore,D-InSAR is more used to monitor applications which is a kind of large surface deformation phenomena in a short period of time,such as seismic deformation.SBAS-InSAR makes up for some shortcomings of D-InSAR.SBAS-InSAR requires a larger amount of data,but it is more suitable for monitoring fine deformation under a wide range.Therefore,it is used more in applications such as urban land subsidence and deformation of mining areas.The growing maturity of InSAR in deformation monitoring applications is due to the continuous innovation of technology,and on the other hand,the continuous fineness of InSAR satellite image data,especially the short-time baseline InSAR satellites that achieve seamless coverage in the world.The development of InSAR satellites provides important data source.