摘要
三江地区位于青藏高原东南缘,川滇菱形块体的西侧.受陆-陆板块碰撞作用的影响,构造活动强烈,地震活动频繁.为研究该区的应力环境、构造特征及二者间的关系,本文使用三江流动线性地震台阵SL-Array(2016-12—2017-05)和国家固定地震台网(2015-01—2017-12)记录到的地震波形资料,运用剪切波分裂分析技术研究三江地区上地壳各向异性研究.计算得到该区域快剪切波优势偏振方向为NNW向,与区域主压应力方向一致.结果显示各向异性特征有分区性,以维西—乔后断裂和小金河—丽江断裂为界,将线性台阵划分为A、B和C三个区域.A区快波优势偏振方向表现出与区域主压应力方向的一致性.B区局部构造复杂,快波优势偏振方向表现为近NS向.C区结果比较离散,无明显快波优势方向.自西向东,研究区域快波优势偏振方向表现为NNW至近NS向的变化趋势.计算得到研究区域慢剪切波时间延迟为2.8±1.7 ms·km^-1,其中B区最大,A区最小,反映了该区地壳介质各向异性强度的不均匀分布,也揭示了区域构造复杂程度与地震各向异性强度的关系.
The Sanjiang region,located on the southeastern margin of the Tibetan Plateau and the southwestern Sichuan-Yunnan rhombic block,has strong tectonic activity and frequent seismic activity due to the effect of continental collision.In order to study the stress environment,structural characteristics and their relationship in this region,this paper uses the seismic waveform data recorded by the Sanjiang Temporary Linear Seismic Array-SL Array(2016.12—2017.05)and the National Seismic Network(2015-01—2017-12)to study the anisotropy of the upper crust by applying the systematic analysis method(SAM).The results show that the dominant polarization direction of the fast shear waves in this region is NNW,which is consistent with the direction of the regional principal compressive stress.Bounded by the Weixi-Qiaohou fault and the Xiaojinhe-Lijiang fault,the study region can be divided into three subregions:A,B and C.The polarization direction of the fast waves in subregion A is NNW,which is consistent with the direction of the regional principal compressive stress.The local structure of subregion B is complex,and the polarization direction of the fast waves in this subregion is NS.The results of the subregion C are discrete,with no obvious fast wave dominant direction.From west to east,the dominant polarization direction of the fast waves in the SL Array area varies from NNW to NS.The time delay of the slow waves is 2.8±1.7 ms·km^-1.Time delay in subregion B is the largest,however that in subregion A is the smallest.This phenomenon indicates that the anisotropy intensity in the crust is distributed unevenly and may be closely related to local tectonic complexity.
作者
吴鹏
高原
陈安国
石玉涛
WU Peng;GAO Yuan;CHEN AnGuo;SHI YuTao(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Key Laboratory of Earthquake,Institute of Earthquake Science,China Earthquake Administration,Beijing 100036,China;Handan Central Seismic Station,Hebei Earthquake Agency,Handan Hebei 056001,China;Innocative Research Team of Hebei Earthquake Agency for Seismograghs Calibration,Valuation and Selection of Observation Sites,Shijiazhuang 050021,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第3期1104-1116,共13页
Chinese Journal of Geophysics
基金
国家自然科学基金重点项目（41730212）
国家重点研发计划（2017YFC1500304）联合资助
关键词
青藏高原东南缘
三江地区
地壳各向异性
剪切波分裂
Southeastern margin of the Tibetan Plateau
Sanjiang region
Seismic anisotropy
Shear-wave splitting
