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A GIT algorithm for simultaneous estimation of seismic source, site response and regional-distance dependent attenuation parameters: application to synthetic and real data
Journal of Seismology ( IF 1.6 ) Pub Date : 2021-01-12 , DOI: 10.1007/s10950-020-09975-8
I. Grendas , N. Theodoulidis , F. Hollender , P. Hatzidimitriou

The generalized inversion technique (GIT) of earthquake recordings is a useful tool in retrieving seismic source spectra, attenuation path parameters and site transfer functions (TF). Further understanding of these three fundamental factors which control seismic ground motion constitutes one of the main challenges in seismology. Especially, the site TF estimation is an important objective that can significantly contribute to seismic hazard assessment. In this study, a parametric GIT algorithm (in MATLAB (The MathWorks, Inc., Natick, Massachusetts, United States, 2017)), based on the one proposed by Drouet et al. (Bull Seism Soc Am 98:198–219, 2008a), is developed, by introducing distance- and regional-dependent attenuation parameters for geometrical spreading and anelastic attenuation terms, respectively. This step is aimed at a more detailed investigation of attenuation path, anticipating to improve the knowledge of all three fundamental factors controlling seismic ground motion. The algorithm is based on a Gauss-Newton iterative inversion method, using initial reasonable model parameters. Source term is parametrically investigated for seismic moment and corner frequency, which can be simultaneously controlled with respect to stress drop. A synthetic dataset, approximating a simplified real dataset was inverted by the proposed inversion algorithm examining its computational validity. Four tests were implemented, with or without reference condition, providing encouraging results. The applicability of the algorithm is supported by the inversion of a real dataset which was also examined by Grendas et al. (Bull Earthq Eng 16:5061–5094, 2018) using a uniform attenuation model in GIT. Approximately 9% reduction of the misfit between real and computed data from the inverted model data is achieved, showing the effectiveness of the proposed algorithm.



中文翻译:

一种同时估算地震震源,场地响应和区域距离相关衰减参数的GIT算法:应用于合成和真实数据

地震记录的广义反演技术(GIT)是检索地震震源谱,衰减路径参数和场地传递函数(TF)的有用工具。对控制地震地震动的这三个基本因素的进一步理解是地震学的主要挑战之一。特别是,现场TF估算是一项重要目标,可以极大地有助于地震危险性评估。在这项研究中,基于Drouet等人提出的一种参数化GIT算法(在MATLAB中(MathWorks,Inc.,Natick,Massachusetts,United States,2017))。(Bull Seism Soc Am 98:198–219,2008a)是通过引入分别依赖于距离和区域的衰减参数来分别进行几何扩展和非弹性衰减项而开发的。此步骤旨在对衰减路径进行更详细的研究,以期提高对控制地震地面运动的所有三个基本因素的了解。该算法基于Gauss-Newton迭代反演方法,使用初始合理模型参数。对震源和拐角频率进行参数研究,可以相对于应力降同时控制源项。拟议的反演算法会检查合成的数据集,将其简化为近似的真实数据集,然后检查其计算有效性。在有或没有参考条件下进行了四项测试,提供了令人鼓舞的结果。该算法的适用性由真实数据集的反演得到支持,Grendas等人也对此进行了检验。(Bull Earthq Eng 16:5061–5094,2018)在GIT中使用统一衰减模型。从逆模型数据中,实数据和计算数据之间的失配大约减少了9%,显示了所提出算法的有效性。

更新日期:2021-01-12
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