The Identification And Application Of Active Fold Scarp And Its Kinematic Models

The blind thrust,a type of faults that does not cut up to the surface,can trigger strong,destructive earthquakes.It is challenged to assess seismic hazards of these active faults due to their weak coseismic surface deformation and unclear coseismic colluvial wedge deposits.Try to use the method of fold scarp,which is formed by blind thrust related fold,and interpret seismic reflection profile to solve this difficult problem.Above all,in terms of the relationship between the structure of fault and fold scarp,the fold carps can be classified into the following types: syncline-fault bend fold scarp,anticline-fault bend fold scarp,fault detachment fold scarp,wedge thrust fold scrap,fore fault propagation fold scarp,back fault propagation fold scarp and trishear fore fault propagation fold scarp.In the west Himalaya Main Frontal Thrust fault(MFT)research area,by combining detailed geologic and geomorphic mapping,differential GPS survey,two strike parallel fault scarps and one fold scarp are found.According to the field work and relevant fold scarp theory,geometric and kinematic models of this fold scarp are rebuilt and the uncertainty of the angle of two faults is discussed.The attitude of two faults is determined by using the models,then the horizontal shortening quantity is restricted respectively by the relief of fault and fold scarp method.Optical Stimulated Luminescence and AMS 14 C samples are collected respectively from the youngest terrace and the horizontal shortening rate of this terrace is calculated.This late Holocene shortening rate provides valuable data(is very important)for Himalaya Main Frontal Thrust fault.In the Dushanzi anticline research area in the North Tianshan,seismic reflection profile is interpreted by using thickness-relief method,and the total horizontal shortening quantity of the far west limb of Dushanzi anticline and the depth of detachment layer are obtained.,Different time-scale horizontal shortening quantity which every terrace records is calculated by using excess-area balance method and differential GPS survey date of the west limb terrace of Dushanzi anticline.By combining detailed geologic and geomorphic mapping and differential GPS survey,fore fault propagation fold scarp is found in the north limb in the Dushanzi anticline and geometric and kinematic models of this fold scarp are rebuilt,which sheds new light on the research of Dushanzi anticline.