chinalgq_v1.0: Seismic Lg-wave Attenuation Model in China
Description:
Continental China is characterized by complicated tectonics, incorporating ancient cratons and orogenies from different geological periods, resulting in considerable large continental earthquakes. However, the tectonic interplay among geological blocks and the mechanisms of intra-continent earthquakes remains to be further explored. The amplitude attenuation of seismic Lg-wave during its propagation is closely related to the crust's temperature, fluid content, and strength. Thus, Lg attenuation helps investigate crustal deformation and evolution. However, the lack of a nationwide, high-resolution, and broadband Lg-wave attenuation model has impeded the application of amplitude measurements under a consistent attenuation framework. This study obtained a new Lg-wave attenuation model for China based on waveforms from 2,318 earthquakes at 1,041 permanent stations. Using an established tomographic scheme, Lg attenuation was solved independently at individual frequencies between 0.05 and 10.0 Hz. To accelerate the convergence and improve the robustness of the solution, we started with an initial Lg attenuation model compiled from a series of previous studies. The checkerboard test demonstrated that the resolution reached 1.0°, and bootstrap resampling estimated the relative uncertainty in Q to be less than 5%. The lateral variations in the resultant Lg-wave Q model corresponded to regional tectonics. High Q values were observed in stable geological blocks in south China and Tarim, whereas active regions, including the Tibetan Plateau, were characterized by significant low-Q anomalies. The average Q over 0.2 to 2.0 Hz appeared uncorrelated with crustal thickness but showed a linear correlation with the strain rate and heat flow, suggesting that crustal deformation and temperature were the primary factors influencing the Lg attenuation. Therefore, the Lg Q could indicate the crust's mechanical strength, revealing the collage pattern of new and old geological blocks in China. This research was supported by the National Natural Science Foundation of China (42104055, U2139206).
Session: Earth’s Structure from the Crust to the Core - II
Type: Oral
Date: 4/16/2025
Presentation Time: 10:30 AM (local time)
Presenting Author: Xi
Student Presenter: No
Invited Presentation:
Poster Number:
Authors
Xi He Presenting Author Corresponding Author hexi@mail.iggcas.ac.cn Chinese Academy of Sciences |
Lian-Feng Zhao zhaolf@mail.iggcas.ac.cn Chinese Academy of Sciences |
Xiao-Bi Xie xxie@ucsc.edu University of California, Santa Cruz |
Lei Zhang leizhang@pku.edu.cn Peking University |
Zhen Liu liuzhen2020@mail.iggcas.ac.cn Chinese Academy of Sciences |
Zhen-Xing Yao yaozx@mail.iggcas.ac.cn Chinese Academy of Sciences |
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chinalgq_v1.0: Seismic Lg-wave Attenuation Model in China
Category
Earth’s Structure from the Crust to the Core