The Monitoring Of The Surface Deformation Base On The InSAR Technology

The ground deformation is the shifting phenomenon in vertical or horizontal direction which caused by earthquakes, volcanic activity, landslides and ground subsidence, or other factors. Many countries and areas have the ground deformation in different levels, so it had endangered the human survival environment in different degrees, and had been one of the main geological disasters.Interferometric Synthetic Aperture Radar, InSAR is a new type of technique on earth observation,developed in the 20th century, and it has numbers merit such as high spatial resolution, high precision and block matrix measure, etc. Radar interference measurement has been widely used in Terrain mapping, deformation field detection of ground, marine research, forest drawings, and land classification and application, etc. In recent years, with geological disasters increasing, such as earthquakes, volcanoes, landslides and ground subsidence, and its harm to human increasing gradually, monitoring strength to this disaster in the world also increases.The occurring of earthquakes, volcanoes, landslides and ground subsidence can arouse terrain deformation in different degrees. Moreover, monitoring to this deformation can forecast disaster and slow down the effects of disaster. We also can analyse and study the mechanism of disaster and strengthen reconstruction efforts after disaster. Now commonly methods of monitoring terrain deformation include GPS control measure, Level measurement, long baseline interference measurement, etc. But these methods is limited in a certain area of measurement, and only monitor discrete points.D-InSAR technology is developed on the basis of InSAR technology, Compared with other monitoring technology of terrain deformation, D-InSAR's advantages mainly embodies in Monitoring area being large and cost being lower, monitoring precision being high, as well as quickly and real-time, etc. And the most important advantage is that monitoring doesnot need human's fieldwork, which ensure human's life safety. Anyhow, D-InSAR has been one of the most effective methods in monitoring ground deformation. Based on learning of synthetic aperture radar measurement and understanding of cause of terrain deformation, this article correlate InSAR technology and monitoring terrain deformation. After grasping SAR, InSAR, tne D-InSAR basic principle and data processing platform of DORIS software, so as to analyses the key algorithms of InSAR data preprocessing. During the SAR data preprocessing with DORIS software, we use the Fourier algorithm to registrate and use the recursive least square algorithm to resample the image.In adittion, we use the orbit parameters to calculate the Flat-erath effect and remove its impact. In the process of phase unwrapping, we apply unwrapping a third party phase modules which is developed by Stanford University for free.The idea of this module is based on network programming method.Extracting information of ground deformation of study areas using three orbits differential interference, and then analying differential interference map. We found a butterfly shaped deformation area in differential interference map, and the color in this area changes cyclicly.The phase changes of 2πin the differential interference contrast map is embodied by color circle and the actual surface deformation is 2.8cm, that is, one color circle represents the actual 2.8cm surface deformation(this deformation value is caculated from Radar line of sight ).Through the carefull observations about butterfly-shaped figure, we found that the upper and lower Valvular,s color change is opposite,indicating that one is rising ang another is dipping. Finally, the largest value in decline is between17.7cm and 29.7cm in rising.Compared with deformation interferometers picture of the same research area from Sensing LABS of the university of Zurich, German geological research center, and German aerospace center, we found that the deformation area shape and the number of figure we had got in this study is the same as the results from other laboratories.