Abstract: ETM remote sensing image and 30 m resolution ASTER DEM data are treated using ArcGIS, and three-dimensional digital elevation model of the northern segment of Shenzha-Dingjie graben with remote sensing image is built, combined with field investigattion, the overall of landscape characteristics of the graben is analysised. On the base of field observation of the main faults, as well as the spreading of graben′s fault from remote sensing interpretation, we found that the faults in half-graben is composed by a east dip major fault with a series of synthetic sub-faults and antithetic sub-faults. Based on half-graben system model, a simple book oblique model is used to calculate the depth of detachment surface and the magnitude of stretch in the graben system. The depth between 3.6~9.7 km is basically consistent to the focal depth in the region, which prove that seismic activity concentrated in the vicinity of the detachment surface. Finally, the graben formation mechanism is discussed. The stress of upper crust is decoupled with lower crust′s due to Indian plate extrusion, and the upper crust moves south and east from gravity, thus the half-graben dip east.

Key words: Shenzha-Dingjie graben, Structure model, Fault activity, Depth of detachment surface