Spatio-temporal Variation of Stress Field in the Badong Section of the Three Gorges Reservoir
GENG Jun
DONG Jianhui
ZHANG Chi
WANG Defeng
Abstract：Taking the Badong section of the Three Gorges Reservoir(30.98°N～31.17°N,110.09°E～110.55°E)as the study area,this study analyzed waveform data from 45 earthquakes with ML≥2.5 recorded between 2013 and 2018 by 22 sub-stations of the Three Gorges Digital Telemetry Seismic Monitoring Network.Focal mechanism solutions were determined using the multi-station P-wave first-motion polarity method,and normal stress inversion of the focal mechanisms was conducted using the MSATSI software with a damped regional stress inversion approach.The results show that:① The 45 ML≥2.5 earthquakes in the Badong reservoir section were predominantly distributed along the Yangtze River,with strike-slip mechanisms dominating the focal solutions;② The maximum principal compressive(σ1)and extensional(σ3)stress axes exhibited spatially heterogeneous orientations:in the eastern Dongrangkou area,σ1 axes trends from NWW to nearly EW,while σ3 axes is aligned approximately NS;in the western Dongrangkou area,σ1 axes is oriented NE,and σ3 axes trends NW;③ Focal mechanisms of five ML≥4.0 earthquakes showed good consistency with the annual stress field inversion results;④ Most of the 45 ML≥2.5 earthquakes occurred during high-and low-water-level stages of the reservoir,suggesting a statistically significant temporal clustering pattern.
Keywords：Badong Dongrangkoufocal mechanism solutionstress field variation
Publication Date：2025-03-31
Online Publishing Date：2025-10-10(First online date of this platform, not the publication date of the document)
Pages：7( 70-76 )