Estimation of Site Effects and Equivalent Source Parameters of Wenchuan Earthquake Based on Generalized Chaotic Particle Inversion Technique

IF 2.6 3区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS
Ke-Lin Chen, Xue-Liang Chen, Jingyan Lan, Li-Jun Qiu, Yi-Ling Zhu
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Abstract

Based on the advantages of the chaos particle swarm optimization algorithm and the generalized inversion technology, this article estimates the source parameters and site effects of the Wenchuan earthquake. We used 440 sets of strong-motion records obtained from 43 aftershocks, and the area covered by the records was divided into subregions A and B. Initial separation of source, path, and site from the seismic spectra of subregions A and B using generalized inversion technique and then the source-site optimization model is established using chaotic particle swarm technology. From path-corrected records, we obtained absolute site effects for 33 stations and equivalent source parameters for 43 earthquakes. We made the following conclusions: (1) The moment magnitude Mw was lower than the local magnitude MLdetermined by China Earthquake Network Center. The self-similarity of the Wenchuan earthquake was confirmed. The stress drop averaged 2.31 MPa, and it was independent of the magnitude size and focal depth. (2) In the frequency 1–10 Hz, the quality factor values in subregions A and B are 110.9f0.6 and 116.1f1.2. The decay rate of the crustal medium in the western region of the west Sichuan plateau is significant compared to the eastern part. (3) Bedrock stations 51MXT and L2007 have site effects within a certain frequency. The effect of slope topography on site predominant frequency is not apparent, and the site effects increase with the increase in elevation. The shape of the site amplification curve is more similar in the middle- and low-frequency bands, and different attenuation phenomena will appear in the high-frequency band.
基于广义混沌粒子反演技术的汶川地震场地效应和等效震源参数估计
本文基于混沌粒子群优化算法和广义反演技术的优势,估计了汶川地震的震源参数和场地效应。利用广义反演技术从 A、B 分区的地震频谱中初步分离震源、路径和场址,然后利用混沌粒子群技术建立震源-场址优化模型。通过路径校正记录,我们获得了 33 个台站的绝对震源效应和 43 次地震的等效震源参数。我们得出以下结论:(1)矩震级 Mw 小于中国地震台网中心确定的当地震级 ML。证实了汶川地震的自相似性。应力降平均为 2.31 MPa,且与震级大小和震源深度无关。(2) 在 1-10 Hz 频率下,A、B 分区的品质因数值分别为 110.9f0.6 和 116.1f1.2。川西高原西部地区地壳介质的衰减速率较东部地区明显。(3)基岩站 51MXT 和 L2007 在一定频率内有场地效应。斜坡地形对站点主频的影响不明显,站点效应随海拔的升高而增大。站点放大曲线的形状在中、低频段较为相似,在高频段会出现不同的衰减现象。
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来源期刊
Seismological Research Letters
Seismological Research Letters 地学-地球化学与地球物理
CiteScore
6.60
自引率
12.10%
发文量
239
审稿时长
3 months
期刊介绍: Information not localized
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