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The spatial distribution and characterization of a heavily damaged area can be determined by studying surface ruptures of seismogenic faults.If the distribution of surface ruptures can be obtained shortly after they occur,then areas heavily damaged by an earthquake can be readily identified.The information can then be used as a guide for earthquake relief programs.In this paper,an intensity offset-tracking method applied to an ALOS PALSAR image is used to map the Yushu earthquake rupture and to identify the faults activated by the earthquake.Azimuthal displacement analysis indicates that the surface rupture is about 55 km long,running from the epicenter to the southeast,trending N310°W,with a relative displacement of～1 m characterized by sinistral slip.The result of range displacement observations indicates that the north wall of the fault is dominated by decreases(i.e.,uplift in line of sight observations) ,whereas in the south wall of the fault,the range displacement is dominated by increases(drops in line of sight observations) .Given the position from which the images were recorded,this means that the north wall moves westward,and the south wall move eastward,i.e.,left-lateral slip motion across the fault.Finally,an earthquake disaster assessment using computer-assisted image analysis software shows that buildings near the fault rupture have been destroyed most heavily;therefore,the shape of the heavily damage belt is controlled partially by the fault rupture’s geometry and the damage degree relates to the magnitude of displacement field.
The spatial distribution and characterization of a polarizing damaged area can be determined by studying surface ruptures of seismogenic faults.If the distribution of surface ruptures can be shortly after they occur, then areas researched by the earthquake then be used as a guide for earthquake relief programs. in this paper, an intensity offset-tracking method applied to an ALOS PALSAR image is used to map the Yushu earthquake rupture and to identify the faults activated by the earthquake. Azimuthal displacement analysis indicates that the surface rupture is about 55 km long, running from the epicenter to the southeast, trending N310 ° W, with a relative displacement of ~ 1 m characterized by sinistral slip.The result of range displacement communications indicates that the north wall of the fault is dominated by decreases (ie, uplift in line of sight observations), and in the south wall of the fault, the range displacement is dominated by increases (drops in line of sight observations) .Given the position from which the images were recorded, this means that the north wall moves westward, and the south wall move eastward, ie, left-lateral slip motion across the fault. Finally, an earthquake disaster assessment using computer-assisted image analysis software shows that buildings near the fault rupture have been destroyed most heavily; therefore, the shape of the heavily damage belt is partially partially controlled by the fault rupture’s geometry and the damage degree to the magnitude of displacement field.