Mulit-source SAR Remote Sensing Data for Rapid Response to Wenchuan Earthquake Damage Assessment

Synthetic Aperture Radar(SAR) has significant advantages in disaster monitoring that are all weather,independent of illumination imaging capabilities and strong stereoscopic sense.SAR technology played irreplaceable role in rapid response to Wenchuan Earthquake monitoring and damage assessment.Wenchuan Earthquake generated numerous of landslides,landslide lakes and dams,as well as debris flows.Their quantity,scale and dimension brake historic records.Landslides buried towns and villages,blocked up river channels which inundated villages and heavily destroyed the road networks and made the rescue work extremely difficult.The hardship of rescue efforts was beyond of human imagination in Wenchuan Earthquake.With high resolution SAR images we detecte a great deal of landslides and landslide lakes.Those giant catastrophic landslides reach very large size and scale.One of the largest landslides we detecte has total area of 7 km2 and fly distance of 4 km.They fly from one side of the river bank to the opposite bank.It is hard to explain their behavior and scale with ordinary concept of landslide.Moving such amount of material needs tremendous energy.Does Wenchuan Earthquake provide such amount of energy? Why does Wenchuan Earthquake generate so many seismic secondary disasters? Certainly geosciences community needs further research to solve this puzzle.The microwave remote sensing division in Institute of Remote Sensing Applications made 7 reports on Tangjiashan landslide and Landslide Lake,Beichuan county with multi-temporal SAR images,7 reports on other landslides and landslide lakes,1 report on building damage assessment for several counties,including Anchang town,Huagai Town,Mianzu City and Luojiang City.All the reports were delivered to central and local government,ministries and rescue teams.This paper summaries the work that has been done for Wenchuan Earthquake.This paper presents the SAR image interpretation on building damage assessment,landslide and landslide lake monitoring,especially their characteristics on SAR images.The damaged building normally has no clear texture or shadow in contrast with buildings in good conditions.Owing to the good stereoscopic sense of SAR images,we can identify the back scar,debris deposit,fly trace and measure the total area and the flying distance of a landslide.With continuously acquired multi-temporal SAR images,including TerraSAR-X and COSMO-SkyMed satellite SAR images,we can track the development of a landslide lake such as Tangjiashan Landslide Lake.As water level rising,the small towns such as Xuan Ping,Zhicheng and village Sheng Kenzi are inundated.The Xuan Ping Town is finally total underwater.Many roads along the Jian River are inundated as well.The tail of Tangjiashan Landslide Lake extends toward upstream gradually,and widens the river channel obviously.All the information extracted and evaluation delivered from SAR images made great contribution to the decision making and rescue action.