Temporal variations in coda attenuation associated with the 2008 Wenchuan(M_(W)7.9)Earthquake in SW,China  

作　　者：Junhua Hu Guoxin Zhang Liyun Fu Yan Zhang Songhui Li 

机构地区：[1]State Key Laboratory of Simulation and Regulation ofWater Cycle in River Basin,China Institute ofWater Resources and Hydropower Research,A-1 Fuxing Road,Beijing 100038,China [2]Department of Structures and Materials,China Institute of Water Resources and Hydropower Research,A-1 Fuxing Road,Beijing 100038,China [3]Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao 266580,China [4]Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,No.19,Beitucheng Western Road,Beijing 100029,China [5]University of Chinese Academy of Sciences,Beijing 100049,China [6]Innovation Academy for Earth Science,Chinese Academy of Sciences,No.19,Beitucheng Western Road,Beijing 100029,China

出　　处：《Geodesy and Geodynamics》2021年第6期424-440,共17页大地测量与地球动力学（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.41874161 and No.41720104006);the Youth Innovation Promotion Association Foundation of the Chinese Academy of Sciences(No.2019069);Guangdong Provincial Key R&D Program(No.2019B111105002)。

摘　　要：In this study,waveform data obtained from Western Sichuan Seismic Array(WSSA)in China was utilized to reveal the temporal variations in coda attenuation around the eastern Tibet Plateau and Western Sichuan.Based on the single-scattering model,coda attenuation factor QC^(-1) is calculated in narrower overlapping frequency bands at 1.0-24 Hz by measuring the coda decay rates for local earthquakes before and after the Wenchuan mainshock.The temporal variations in coda attenuation are investigated within three periods.The periodⅠlasted from January 2007 to the end of 2007.The periodⅡlasted from January 2008 till Wenchuan earthquake.The periodⅢlasted from the mainshock to the end of 2008.The resulted temporal variations demonstrate an increase in average QC^(-1) by approximately 35%-45%in the vicinity of Longmenshan and 30%-35%in Sichuan Basin after the Wenchuan earthquake in lower frequency bands within 1.25-8 Hz.On the contrary,the average QC^(-1) is shown to decrease by approximately10%-18%in southern segment of Longmenshan,15%-38%in the Chuan-Dian block,and 10-12%in the South China block.These results are confirmed by a statistical t-test at 99.9%confidence level No statistically significant change in QC^(-1)(<10%)is found in the Songpan-Ganzi block after the mainshock.Temporal variations of coda attenuation differ significantly in individual blocks after the mainshock.The coda attenuation is proposed to be a beacon to tectonic static stress changes associated with the Wenchuan earthquake.

关 键 词：Wenchuan earthquake Single-scattering model Coda attenuation Tectonic static stress 

分 类 号：P315.2[天文地球—地震学]