Main Geological Hazards Along The Karakoram Highway And Observational Studies By InSAR

Karakoram Highway connecting Xinjiang of China and the northern of Pakistan is a extremely important transport hub,which is an important corridor from Western China,even the Middle East to the South Asian Subcontinent,which is a part of the ancient Silk Road.Karakoram Highway through the west junction structure of Qinghai-Tibet Plateau where is one of the most intense area of internal and external dynamic action,characterized by tectonical action,deep river,steep terrain,3,000 to 5,000 meters of valleys elevation difference,and marked by obvious vertical climatic zonation,strong Glacier erosion and outstanding geological hazards,all of that restrict the construction of infrastructure along China-Pakistan Economic Corridor.Due to geographical location and natural conditions,few of research and summary had been done systematicly for geological hazards,even more,deeply analysises are also lacking for the potential hazards along the Karakoram Highway.In this paper,we summarized the types and distribution of geological hazards along the Karakoram Highway,and initially revealed the causes of them.,by geological background analysis,optical remote sensing interpretation and field geological survey,and used InSAR technology,which characterized by high-precision,large-scale,non-contact,for the view of surface deformation in Hunza valley.as a result,identified the creep slope of geological disasters,then analyzed the types,causes,deformation and distribution characteristics.The main conclusions are as follows:(1)Based on field investigation and relevant data of previous studies,summarized the feature of regional tectonic and active faults across the Karakoram Highway,and summarized the development and distribution for geological hazards fragmently from Kashigar to Thakot Bridge,including the valley of Ganzi,the sections from Khunjerab to Sost Sost to Gilgit,Gilgit to Chilas and Chilas to Thakot,which are marked by disaster,the valley of Ganzi and the section from Khunjerab to Chilas are the most among them for glacier debris flow.(2)The successed observations for the surface deformation aranged from millimeter level to hundreds meters by combination of D-InSAR,IPTA-InSAR and Offset-tracking tecnologies,not only overcome the decorrelation problem within the long span of time,but also achieved the monitoring for large rate deformation,enriched the application of InSAR technology in the field of engineering geology,improved the processing methods of InSAR technology.The results proved that the time-series InSAR technology can recongnize slowing motion landslide exactly and effectively under the condition of serious Satellite orbit errors and lage space baselines,not only effectively identify the motion of Moraine,Stream shipo,landslide and other kinds of surface erosion,but also monitor rapid glacier displacement.(3)Slope creep landslide and other geological hazards are significant along Hunza valley,and the back cracks of slowing-motion landslide are evident.More,landslide slip rate significantly faster than the other times from 2008 to 200,is strongly affected by the same period of precipitation and temperature anomalies.Creep landslide average slip rate between 20～30mm/yr.And Attabad landslide that blocked the Karakoram Highway in 2010,had the rapid deformation of 27.8～83.8cm/yrs,the results can benefit the monitoring and early warning,even the risk assessment of local geological disasters.(4)The glaciers on the north side of Hunza valley are large scale glaciers worldwide,that belong to continental glacier,the rate of movement of which is far greater than kongur and Muztag mountain glaciers,and there is a connection between rate of movement and seasonal migration,in summer,the rate more bigger,while in winter more small.The movement pattern of Pasu glacier is similar as longitudinal wave for energy transferring.