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.
PS InSAR技术在微小形变的监测中有着独特的优势,但同时受到数据量的严重制约。本文以形变速率稳定的怀来县城为实验区,利用15景ASAR数据,依据主影像选择和高程改正选取了三种略有差异的模型分别进行PS处理,并对形变提取中的相位解缠、基线改正和高程改正进行误差分析。结果表明,小数据集的相位解缠和高程改正在部分PS点上容易发生错误,但形变估计整体上能够正确反映实际情况。三个模型中MS(Multi-Reference Single Re-gression)模型得出结果最为可靠。小数据集解算的整体PS点质量不高,可以在满足PS点密度要求的前提下,降低相位标准偏差阈值以提高解算的可靠性。
