地震学报2012，Vol.34Issue(2)：171-190,20.DOI:10.3969/j.issn.0253-3782.2012.02.005
基于Langston分解和Hilbert变换约束的区域偏量矩张量反演方法及其应用
Regional deviatoric moment tensor inversion based on Langston's decomposition and Hilbert transform constraints and its application
摘要
Abstract
Based on Langston's decomposition theory and Minson and Dreger's near-field displacement formula, this paper proposes a deviatoric moment tensor inversion method. Waveform's envelop function calculated from Hilbert transform is introduced to stabilize the inversion. The method is successfully tested with synthetic data. Numerical experiment result shows that the method has decent robustness and stabilization. Specific results are as follows. (1) While the velocity structure and earthquake location are exactly known, the solution will be accurate and stable (Kagan angle＜5°, the error of double couple component percent, noted as DC%, within ±5%), despite of high noise level even reaching to 30% of original signals. (2) While random disturbances on wave arrival time are limited within ±3 s, the moment tensor solutions inverted in 0. 01-0. 1 Hz frequency range are still entirely stable. About two-thirds of solutions can be considered to be very close to the true solution (Kagan angle＜15°, DC% within ±5%), and about 90% of solutions have a small deviation to the true ones (Kagan angle＜30°, DC% within ±10%). It shows that the method has good compatibility with crustal anisotropy and lateral heterogeneity. (3) The test results under various crust models show that the velocity model has important effect on inversion result. If a 1D model being close to the mean model of true crust structure is used, the inversion can retrieve near-real solution. If the model is a little different from the true model (no more than 10% error), the solution would be close to the real one; if the error exceeds 10% , even reaching to 20% , of original signals, the solution will have notable bias. (4) Earthquake location error mainly affects focal depth determination, accordingly cause spurious non-DC component in final solution. But, with the constraint of pure devia-toric moment tensor, the fault parameters retrieved from inversion have little bias from the real one. (5) In case of sparse data (3 stations at least) and worse station coverage (less than 60°), we can still get relatively correct solution from the method under mean crust model. The method is applied to 24 Oct. 2010 Zhoukou-Taikang Mw4. 7 event in Henan province, China. The optimized solution retrieved by this method is consistent with that estimated from P wave polarity data.关键词
矩张量反演/数值试验/震源机制/速度模型Key words
moment tensor inversion/ numerical test/ focal mechanism/ crustal model分类
天文与地球科学引用本文复制引用
郑建常,陈运泰..基于Langston分解和Hilbert变换约束的区域偏量矩张量反演方法及其应用[J].地震学报,2012,34(2):171-190,20.基金项目
地震科技星火计划项目(XH12028Y)、全国地震大形势跟踪预测项目(1011600707)、中国地震局监测预报司震情跟踪定向工作任务(201102220102)及山东省地震局重点科研项目(JJ1103y)联合资助. （XH12028Y）
