摘要
研究表明,远震直达体波波形（P波、SH波）是有效反演中强地震（M5.5-7）震源参数的重要资料.但是当震中距较大时,核幔边界全反射波ScS会进入SH波反演窗口,其未被传统的基于体波震源参数反演算法所考虑,从而导致反演结果偏差.本文通过TEL3与fk方法合成理论地震图,使用Jackknifing统计方法定量测试了不同情况下ScS震相对远震体波反演的影响.结果表明,当反演数据震中距位于70°-90°时,ScS震相会造成震源质心深度1km左右、机制解最大8°的系统偏差;使用震中距40°-90°的SH波进行抽样反演,机制解最大系统偏差可达5°;SH波与P波联合反演可减少ScS震相引起的震源参数结果系统偏差.因此,ScS震相对基于射线理论的远震体波震源机制解反演所造成的误差是需要给予考虑的.
Teleseismic body waves（P and SH waves）are essential for obtaining source parameters（focal depth,mechanism,magnitude etc.）of moderate-strong earthquakes（M5.5-7）.However,ScS waves could complicate SH waveforms,especially at large distances where the time interval between the direct SH and ScS waves is smaller than the time window in inversion,which is not taken into account in current inversion methods with teleseismic body waves.Therefore,the artefacts in source parameters could be produced with such contaminated waveforms.Based on TEL3 and fk methods of synthetic seismograms,we use the Jackknifing method to quantitatively test the effects of ScS on focal depth and mechanism in CAPtel inversion.When ScS effect is not considered for body wave data in the epicentral distance range 70°-90°,there are systematicdeviations of 8°for focal mechanism and 1km for source centroid depth between the input and inverted parameters;while there still are system deviations of 5°for mechanism,even though the epicentral distance of data ranges from 40°to 90°.Thus,the deviations caused by ScS in the ray theoretical inversion of teleseismic body waves cannot be neglected.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2016年第6期2014-2027,共14页
Chinese Journal of Geophysics
基金
国家重点基础研究发展计划项目(2014CB845901)
国家自然科学基金(41274069)资助
