论文部分内容阅读
利用星载合成孔径雷达差分干涉测量技术(D-InSAR)和60景日本ALOS/PALSAR1.1级雷达数据,采用两通差分干涉处理模式,对2008年5月12日汶川Ms8.0级地震的同震干涉形变场进行了研究.通过对干涉处理中图象配准、噪声滤波和相位解缠等若干关键算法的优化使用,成功获取了震中周围较大区域的形变干涉纹图和数值化位移场分布图,并通过形变等值线和跨断层剖面线对形变场进行了定量分析,客观揭示了汶川地震地表形变场的全貌及其空间动态变化特征.结果显示,汶川地震造成的地表形变场影响范围很大,但形变主要集中在断层两侧附近区域,在上下盘各约100km以外的远场区形变量较小.按形变幅度和梯度的差异整个形变场可分为三个区域,一个是位于断裂带及其附近的非相干带所指示的强烈变形区,长度约250km,宽度在西南方向约35—15km,在东北方向约15—10km,西南宽东北窄,最大宽度位于汶川和映秀之间,这说明破裂由西南向东北扩展.这一区域是本次地震中形变最强烈,并形成地震地表破裂带的区域,该区域的形变InSAR已无法测出.另一个是位于非相干带南北两侧具有清晰可辨连续并向发震断层收敛的包络状干涉条纹所示的次级变形区,该区域在断层两侧的宽度各约70km,视线向位移为上盘沉降,沉降幅度约在-100cm以上,下盘抬升,抬升幅度约在120—130cm以下.上盘及断层附近干涉条纹相对密集,跨断层形变曲线粗糙锯齿,显示形变过程复杂,变形非均匀性突出.沿发震断层走向出现多处规模不等的局部隆起和沉降.远离发震断层的发散状宽缓条纹分布区域为远场弱变形区,形变量约为-20—30cm.这些形变特征反映了发震断层运动的分段差异性、上下盘之间的相对逆冲性及逆断层型地震上盘破坏的复杂性.初步分析认为汶川地震发震断层的运动模式可能不是上盘向下盘的单向逆冲推覆,而是上下盘的相对逆冲挤压.
Using the differential interference measurement technique (D-InSAR) of spaceborne synthetic aperture radar (D-InSAR) and the 60-day Japanese ALOS / PALSAR1.1 radar data, a two-way differential interference processing mode was used to simulate the Wenchuan Ms8.0 earthquake on May 12, Co-seismic interference deformation field is studied.The deformation interference fringe pattern and numerical displacement of large area around the epicenter are successfully obtained by optimizing the use of several key algorithms such as image registration, noise filtering and phase unwrapping in the interference processing. Field distribution and quantitative analysis of the deformation field through the deformation contour line and the cross-section line, objectively reveal the whole picture of the surface deformation field and its spatial dynamic change characteristics of the Wenchuan earthquake.The results show that the surface deformation field caused by the Wenchuan earthquake The deformation is mainly in the vicinity of the two sides of the fault, and the deformation in the far-field area is small in about 100km away from the upper and lower plates.The whole deformation field can be divided into three regions according to the difference between the deformation amplitude and the gradient It is a strong deformation zone indicated by the incoherent belt located in and near the fault zone. The length is about 250km, width is about 35-15km in the southwest, about 15-10km in the northeast, narrow in the southwest and northeast, The large width is located between Wenchuan and Yingxiu, indicating that the rupture extends from southwest to northeast, which is the area where the most deforming and seismic surface rupture zone of this earthquake occurred, and the deformed InSAR in this area can not be measured. One is the secondary deformation zone located on the north and south sides of the incoherent zone with enveloping interference fringes which are clearly and continuously identifiable and converge to the seismogenic fault. The width of the fault on both sides of the fault is about 70 km each and the line-of-sight displacement is The settlement of the upper plate is about -100cm, the lower plate is lifted and the lifting amplitude is about 120-130cm. The interference fringes near the upper plate and the fault are relatively dense, and the cross-section deformation curve is rough and jagged, which shows that the deformation process is complicated and the deformation is not uniform Along the seismogenic faults, there are many local uplifts and subsidences with different scales, and the distribution area of divergent and widened stripes away from the seismogenic fault is the far-field weak deformation zone with deformation of about -20-30cm. These deformations The characteristics reflect the subdivision of seismogenic faults, the relative thrust between the upper and lower plates and the complexity of the damage to the thrust fault.The preliminary analysis shows that the movement pattern of the seismogenic fault in the Wenchuan earthquake It may not be a one-way thrusting of the upper plate to the lower plate, but a relative thrusting of the upper plate and the lower plate.