以GPS、D-InSAR和数值模拟联合限定伊朗西北部米树断裂的应变转换机制：从地表到深部

A fault can not disappear without reason, because their motion could always be absorbed and/or transferred by other structures at their ends. Take the Altun Tagh strike slip fault as an example. The fault’s left-lateral strike slip motion is absorbed by crustal shortening, resulted in the uplift of the West Kunlun Mountain to the southwest and the Qilian Shan Range to the northeast. However, how to quantify the strain partitioning mechanism is one of the most difficult scientific problems. In the front zone of the Arabia-Eurasia Plate, there appears the similar phenomenon: one right-lateral strike slip fault, named the North Tabriz fault, is disappeared when entering into the nearly east-west-striking Mishu fault to its northernmost end. In which strain partitioning mechanism that the Mishu fault accommodates the North Tabriz fault’s shearing is still unclear. This study will take the cooperation chance between the Institute of Geophysics and Geology, CAS, with the Geological Survey of Iran on the evolution of the Iranian Plateau, and select the Mishu fault located on the northern continuation of the North Tabriz strike slip fault as our research area. We plan to apply the GPS and D-InSAR technology to measure the activity pattern in the transforming zone between these two faults. In a 3-D view of measuring from surface into simulation at depth, we expect to see whether or not the Mishu fault’s movement is major on thrusting and minor on strike slip shearing and their associated proportions. We hope this research could be helpful to promote our understanding for the strain partitioning mechanism at the end of strike slip faults.

没有无限制延伸的断裂，因为断裂末端的位移总是被其它性质的构造吸收调节掉。以走滑断裂为例，位于青藏高原北缘的阿尔金断裂的左行走滑运动，就在其南西、北东尾端分别被西昆仑山和祁连山的抬升和断裂的逆冲运动吸收调节掉。如何定量化这种转换机制，一直以来都是难点之一。位于阿拉伯板块与欧亚板块碰撞前缘地带的北大不里士断裂呈右行走滑，它向北段延伸至近东西向的米树断裂后逐渐消失，其转换的构造机理目前还不得而知。本申请拟利用参加中国科学院地质与地球物理研究所与伊朗地质调查局共同开展的针对伊朗高原构造演化的合作研究的机会，选取米树断裂作为研究对象，通过对其进行GPS和D-InSAR地表活动速率监测，并结合数值模拟，反演其深部断裂面上的滑移分布，从地表观测再到深部反演，全方位、三维视角地限定米树断裂当前是否以逆冲推覆为主、走滑运动为辅以及各自所占的比重多大，由此探讨走滑断裂在尾端的应变调节机制。

1）应用InSAR和GPS等空间遥测学数据监测伊朗西北部最大规模走滑断裂--北大不里士断裂的震间期地表活动变形，并将两套数据进行联合数值模拟，反演断裂深部滑移的亏损性滑移分布，结合野外地质地貌研究，针对年轻的伊朗高原西北部的大型活动断裂North Tabriz的尾端转换机制进行了定量化研究，获得了创新性结论，即North Tabriz断裂-Mishu断裂带-Maku断裂带之前连为一体，它们的尾端转换控制了地震能量在时空上的跳跃。该模式可以对国内汶川地震与雅安地震之间究竟后者是不是前者余震，提供有益参考..2）应用InSAR、GPS和水准等空间遥测学数据，对位于台湾东北部的宜兰三角形平原，进行了震间期应变调节机制的研究。对从吕宋岛弧与欧亚大陆的弧-陆挤压碰撞到冲绳海槽的弧后拉张的构造转换机制提出了新的构造模型。这一研究，可以对同样处于陆内构造转换带内的应变调节机制提供参考..3) 应用GPS数据分析，结合震源机制解分析，对2014年8月3日鲁甸Ms 6.5地震的蕴震动力学机制进行了定量化解析。提出鲁甸地震是一个孕育在川滇菱形地块向东扩展的模式。该研究可以为地震局系统目前重点研究的川滇实验场项目，提供构造地质学框架以及局部应力构造域的有益参考..4）应用升、降轨Sentinel-1A雷达卫星图像，限定2017年4月5日发生在伊朗东部平原的玛什哈德Mw 6.1级地震的走滑和逆冲推覆分量，由此限定出在伊朗东部斜向碰撞带的前缘地带内，走滑运动协调下的块体间的侧向和旋转运动，也发挥了极为重要的作用。该成果对伊朗东部的地震灾害提供第一手的基础研究数据.