巴颜喀拉地块东北边界三维变形与强震过程研究

2001年以来巴颜喀拉东北边界相继发生了昆仑山口西、汶川、芦山和九寨沟等M≥7强震，为研究多断层系统的强震动力关联及其影响提供了机会。针对该问题，本项目拟从地壳形变、断层反演和力学模拟等方面开展研究工作。具体包括：①基于GPS、精密水准和InSAR资料，采用分段线性约束和数据融合方法得到统一参考基准的三维运动场，通过解析分析和模型反演获取应变率场分布和块体边界滑动结果；②基于构造地质、大地测量、地震活动等资料，建立块体动力学模型研究给出4次强震过程影响下的块体及边界带运动、应变、应力动态结果；③构建局部数值模型和断层反演模型，以大地测量和小震精定位等资料为约束，反演给出东昆仑断裂带东段闭锁程度分布，模拟给出塔藏断裂、龙日坝断裂、龙门山断裂、东昆仑断裂带东段等断层接触、摩擦及流变等力学特性。基于上述研究，揭示研究区域的三维变形特征与力学成因，为认识大陆内部强震成组孕育机理提供支撑。

A series of strong earthquakes (M≥7), such as 2001 M8.1 Kunlun earthquake, 2008 M8.0 Wenchuan earthquake, 2013 M7.0 Lushan earthquake and 2017 M7.0 Jiuzhaigou earthquake, have successively occurred on the northeast margin of Bayan Har block and its adjacent areas, which provides opportunities to study the dynamic relevance and influence of strong earthquakes for the multi-faults system. This project intends to carry out researches in terms of crustal deformation, fault inversion and mechanical modeling. The detailed contents are as follows, 1) We will adopt the subsection-linear constraint and data integration method to get the 3-D velocity field in a uniform reference frame, based on GPS, precise leveling and InSAR data. Then, the regional strain rate field and slip rate of the block boundary will be calculated via analytical and model inversion. 2) In view of the structural geology, geodetic data and seismic activity, the dynamic model of active blocks will be constructed, and the results of relative movements, surface strain rate and stress rate of the block and its boundary zone will be studied under the influence of 4 strong earthquakes. 3) By constructing numerical model and fault inversion model, constrained by geodetic observations and small earthquake relocation, we will inverse the fault locking ratio of east segment of East Kunlun fault, and simulate the fault mechanical properties of the Tazang fault, Longriba fault, Longmenshan fault and east segment of East Kunlun fault, such as contact, friction and rheology properties. The research above will reveal the regional 3-D deformation and its mechanical mechanism, which will provide significant support for recognizing the mechanism of preparation and occurrence of continental strong earthquakes.