摘要
地震位置的准确度是开展高精度壳幔结构研究的重要基础。由于地震台站间距的稀疏性,地震台网发布的地震位置存在较大的水平误差,其深度的不确定性更是其水平不确定性的数倍之多,地震位置准确度还未达到开展高精度结构研究的要求。因此,研究学者需要综合分析多种影响因素且对地震位置进行合理优化后,才可利用它获得较为可靠的壳幔结构。本研究以2019年长宁M_(S)6.0地震为例,使用基于正演的网格搜索定位方法,定性验证了不完备的方位角和难以准确识别的S震相走时会对震源位置的准确性产生较大影响,定量分析了观测数据量和速度模型与震源深度间的制约关系,这些影响因素基本遵循前人已获得的认知准则。另外,该次研究还发现BJT和ZYT地震台站可能存在较大的授时偏差。
The accuracy of seismic locations is an important foundation for conducting better studies on crust-mantle structures.Due to the sparsity of the distance between seismic stations,the seismic position released by seismic network shows a large horizontal error.Moreover,the vertical uncertainty is much greater than the horizontal uncertainty,which is insufficiently accurate to meet the demands of high precision structural research.Therefore,it is significant to conduct a comprehensive analysis of diverse parameters related to hypocentral position and to optimize the accuracy of hypocentral location prior to imaging a more reliable crust-mantle structure.This study used the Changning M_(S)6.0 earthquake as a case study and applied a grid search method based on forward process to relocate earthquakes.The qualitative analysis showed that the accuracy of hypocentral location is significantly impacted by incomplete azimuthal coverage and the difficulty in identifying S-wave arrival.In addition,we quantitatively analyzed the tradeoff relationships from data amount and velocity model to hypocentral depth.These relationships between parameters and position uncertainties suggested a general adherence to a previous criteria for earthquake location.Moreover,we found that the BJT and ZYT seismic stations may have large timing deviations.
作者
张风雪
胡莉娅
李昱
ZHANG Fengxue;HU Liya;LI Yu(SinoProbe Laboratory of Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)
出处
《四川地震》
2024年第2期24-28,共5页
Earthquake Research in Sichuan
基金
自然资源部深地科学与探测技术实验室开放课题(Sinoprobe Lab 202222)
国家自然科学基金(41874072)。
关键词
地震定位
长宁MS6.0地震
定位准则
earthquake location
the Changning M_(S)6.0 earthquake
criteria for earthquake location
