结合台阵反投影技术在MCMC算法下进行多点矩张量/震源机制反演

本项目拟采用贝叶斯反演理论下的MCMC算法､结合台阵反投影技术进行震源复杂性研究,利用后者可直接提供破裂时空分布作为先验信息､MCMC算法可在有限时长内进行高维非线性反演､贝叶斯反演理论可充分利用先验信息并量化不确定性这三项优势,进行多点矩张量/震源机制反演｡项目的核心内容包括:设计反演策略､模型测试､软件编写与实际应用四个部分,研究目标是针对近年来全球范围内一些MW7.5级以上且具有复杂破裂过程的大地震进行多点源模型反演｡相较于矩心矩张量反演与有限断层反演,多点矩张量/震源机制反演因其包含自由参数更多,所以能更详细地描述复杂震源的物理特性,同时也能很好地填补以上两种技术之间的空白,引入MCMC算法与反投影技术也最大程度地避免了物理意义不明确的先验约束并有效节约了计算成本｡项目中涉及的研究方法在了解大地震震源时空特性与震源机制变化等困难科学问题上具有一定理论意义和广泛的应用前景。

This project intends to use the MCMC algorithm under the Bayesian inversion theory combined with the array back projection technology to study the source complexity. The backprojection technology can directly provide the rupture spatial-temporal distribution as prior information. The MCMC algorithm can perform high-dimensional nonlinearity inversion within a limited time. Bayesian inversion theory can make full use of prior information and quantify uncertainty. This project uses these three advantages to perform multi-point moment tensor/focal mechanism inversion. The core content of the project includes four parts: design inversion strategy, model testing, software writing and practical application. The research goal is to carry out multi-point sources model inversion for large earthquakes with MW 7.5 or higher and complex rupture processes on a global scale in recent years. Compared with the centroid moment tensor inversion and the finite fault inversion, the multi-point moment tensor/focal mechanism inversion contains more free parameters, so it can describe the physical characteristics of complex sources in more detail, and it is also fill the gap between the above two technologies. The introduction of MCMC algorithm and back-projection technology avoids the prior constraints of unclear physical meaning to the greatest extent, and effectively saves the calculation cost. The research methods involved in the project have certain theoretical significance and broad application prospects in understanding difficult scientific issues such as the temporal and spatial characteristics of large earthquake sources and changes in focal mechanisms.