利用升降轨InSAR与GPS研究阿尔金断裂带现今滑动分布及孕震凹凸体识别

The Altyn Tagh Fault is the largest and most significant left-lateral strike-slip active fault in the Eurasian plate. It is one of the dangerous areas where high magnitude earthquakes may occur in the future. However, due to the limitation of observation environment and monitoring capability, the distribution density of GPS stations in this area is too low, and InSAR technology has only been applied in several segments with good observation conditions. Therefore, the present-day activity of the Altyn Tagh Fault is still unclear. In this project, we try to combine ascending/descending InSAR and GPS to study the present-day slip distribution and potential seismogenic asperities along the Altyn Tagh Fault. We will carry out the following works. Firstly, three-dimensional crustal deformation fields will be estimated by combining ascending/descending InSAR and GPS measurements. Secondly, slip distribution, locking state and strain rate field of the Altyn Tagh Fault will be inverted based on the three-dimensional deformation field. Thirdly, we will determine the location of potential seismogenic asperities along the Altyn Tagh Fault from jointing the geodetic inversion results and digital seismology data. The research results of this project will have great practical significance for the seismic hazard assessment of the Altyn Tagh fault zone. It has important theoretical value for understanding the role of undeformed blocks and continuum deformation in the Indo-Eurasian collisional models at the northern margin of the Tibetan plateau and studying the geodynamics mechanism of the Tibetan plateau.

阿尔金断裂带是欧亚板块内部规模最大、左旋走滑最显著的活动断裂，是未来可能发生高震级地震的危险区之一。然而，受观测环境和监测能力的限制，GPS测站在该区域分布密度太低，而InSAR技术也只在几个观测条件较好的段落得到了应用，因此阿尔金断裂带现今活动状态尚不清楚。本项目将联合升降轨InSAR与GPS技术揭示阿尔金断裂带现今滑动分布及潜在孕震凹凸体分布，拟开展以下三个方面的研究内容：（1）利用升降轨InSAR数据和GPS观测资料，获取阿尔金断裂带全段落精细三维地壳形变场；（2）以三维形变场为约束，反演计算阿尔金断裂带现今滑动分布、闭锁状态和区域应变率场；（3）联合大地测量反演结果与数字地震学资料，综合判断阿尔金断裂带断层面可能存在的孕震凹凸体部位。本项目研究结果将对阿尔金断裂带的地震危险性评估具有重大现实意义，对认识青藏高原北缘构造变形的端元模式和研究青藏高原区域大的动力学机理具有重要理论价值。

阿尔金断裂带是一条长达2000公里的巨型左旋走滑断层，是青藏高原相对于欧亚板块向东运动的主要左旋走滑构造之一。它也是青藏高原扩张的前沿断层，对青藏高原的隆升和扩张过程及机制有重要影响。本项目通过收集覆盖阿尔金断裂带全段的升降轨Sentinel-1 SAR数据，利用高精度InSAR数据处理技术方法获得了阿尔金断裂带的震间地表形变速率场。然后，利用升降轨InSAR数据和GPS观测资料，获取了青藏高原北缘的三维地壳形变场。通过二维\三维位错模型反演了阿尔金断裂带的断层滑动速率和闭锁状态等运动学参数。综合考虑地质、历史地震和已发表研究成果，对阿尔金断裂的滑动速率空间分布特征进行了定量分析，并探讨了断层几何结构与构造转换以及应力分配关系之间的关联。这一研究对于评估阿尔金断裂带的地震危险性具有重要的现实意义。此外，该项目还为解释大的区域构造运动提供了理论基础，积累了丰富的数据处理和断层面反演的经验。该研究结果对于认识青藏高原构造变形的端元模式以及动力学机理具有重要的理论价值。