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基于星载合成孔径雷达差分干涉测量技术(D-InSAR),利用7个条带共112景日本ALOS/PALSAR raw格式雷达数据,采用两通差分干涉处理模式,获取了2008年5月12日汶川MS8.0地震发震断层周围约450km×500km区域的同震形变干涉纹图。通过对干涉纹图的定性分析,确定了非相干带的分布范围,据此对相位连续条带和相位不连续条带采用不同的相位解缠方案,实现了7个条带的成功解缠,获得了数值化的干涉形变场图像,并通过形变等值线和跨断层形变剖面线等方法对干涉形变场的空间分布和演化特征进行了分析。结果表明:汶川地震造成的地表形变场沿映秀-北川断裂带分布,形变范围很大,但主要集中在发震断层南北两侧各约100km的近场区。其中断层附近由西向东宽约30~15km,长约250km的区域为非相干带,是本次地震中变形最强烈并伴有地表破裂发生的区域,其形变梯度已超出InSAR测度能力。在非相干带两侧宽度各约70km,具有清晰可辨连续完整并向发震断层收敛的包络状干涉条纹区域是次一级形变区,距离发震断层越近,形变梯度和幅度越大,其视线向位移为北盘沉降,南盘抬升。相对于数据条带南北边缘,北盘最大累积沉降量约-110~-120cm,出现于汶川和茂县东北,在理县南震中附近也有一大面积沉降区,沉降位移约为-55~-60cm。南盘最大累积抬升量约120~130cm,出现在映秀西侧震中区,都江堰北及北川附近。南北盘之间的相对最大形变量约240cm,出现在映秀西侧震中附近及都江堰北。在发震断层两侧距非相干带各约70km以外的远场区,干涉条纹稀少,形变量很小,仅在±10cm以下。跨断层形变剖面表明,断层附近及其上盘形变梯度差异大,变形非均匀性突出,而下盘形变过程相对平稳。这些形变差异反映了断层活动的非均匀性及逆断层变形的复杂性。分析认为汶川地震发震断层的运动模式是上下盘相对逆冲运动。
Based on D-InSAR, a total of 112 bands of Japanese ALOS / PALSAR raw radar data were acquired from 7 strips. The two-way differential interference processing mode was used to obtain the data of Wenchuan Coseismic Deformation Pattern in the Approximately 450km × 500km Area Around the MS8.0 Seismogenic Fault. Through the qualitative analysis of the interference pattern, the distribution range of incoherent bands was determined, and different phase unwrapping schemes were adopted for the continuous phase strips and the phase discontinuous strips to achieve the successful unwinding of the seven strips, Obtained the numerical image of the interference deformation field and analyzed the spatial distribution and evolution characteristics of the deformation field by means of deformation contour lines and cross-fault deformation section lines. The results show that the surface deformation field caused by the Wenchuan earthquake distributes along the Yingxiu-Beichuan fault zone, and the deformation range is very large. However, it mainly concentrates in the near-field region about 100km away from the north and south of the seismogenic fault. The area near the fault with a width of 30 ~ 15km from west to east and a length of 250km is a non-coherent zone, which is the area with the most intense deformation and surface rupture in this earthquake. The deformation gradient has exceeded the InSAR measure ability. The width of each side of the incoherent zone is about 70km. The enveloping fringe fringes with clearly distinguishable and continuous complete convergence to the seismogenic faults are secondary deformation zones. The closer the distance to the seismogenic fault, the greater the deformation gradient and amplitude , Its line of sight to the North Platts settlement settlement, Southpan uplift. Relative to the northern and southern fringes of the data strip, the maximum accumulated sedimentation in the northern disk is about -110 ~ -120cm, appearing in the northeast of Wenchuan and Maoxian. There is also a large area of subsidence in the vicinity of the southern epicenter of Li County, with a subsidence displacement of about -55 ~ -60cm . The largest accumulation of Southpan uplift about 120 ~ 130cm, appeared in the Yingxiu epicenter area, Dujiangyan North and near Beichuan. The relative maximum deformation between the North and South plate is about 240cm, appearing in the vicinity of the epicenter on the west side of Yingxiu and in the north of Dujiangyan. In the far-field region about 70 km away from the non-coherent band on both sides of the seismogenic fault, there are few interference fringes and the deformation amount is very small, only below ± 10 cm. The cross-fault deformation profile shows that there is a large difference in deformation gradient near the fault and its upper disk, prominent deformation inhomogeneity, while the deformation of the lower disk is relatively stable. These differences in deformation reflect the heterogeneity of fault activity and the complexity of reverse fault deformation. The analysis shows that the movement pattern of the seismogenic fault in the Wenchuan earthquake is the relative thrusting movement of the upper and lower plates.