首页|云南宾川盆地及周边地震波走时的季节性变化和可能的物理机制

云南宾川盆地及周边地震波走时的季节性变化和可能的物理机制

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基于背景噪声自相关方法,本文计算了云南宾川盆地及周边区域地震波在四个频段的相对走时变化(dt/t),发现存在比较显著的年变和半年变特征,最大变化幅度从0.1～0.2 Hz(7 km左右深度最敏感)的±0.8％逐渐降低至1.0～2.0 Hz(对应1 km以浅介质)的±0.05％.噪声源季节性变化可能是dt/t周期性起伏的一个潜在因素,但雨水和温度与其有更直接的关联性.其中雨水渗透产生的介质孔隙压变化是年变和半年变的重要贡献因素;而温度起伏产生的介质热力学形变,主要对一定深度范围(3 km左右最敏感)的介质有明显的年变影响.不同频段走时变化存在幅度差异和不同步,可能和各频段敏感核的深度范围以及水与热力学形变从地表向深部渗透/传播过程有关.研究表明,环境因素对地下介质的地震波走时有较为显著的影响,区分出它们的贡献,才能更可靠地评估地震构造应力或人文生态环境的变化.
The seasonal variations of the seismic wave travel times and their potential mechanisms in and around the Binchuan Basin,Yunnan Province
The relative seismic traveltimes changes(dt/ts)in four frequency bands for the Binchuan Basin and its surrounding areas of Yunnan Province,were calculated with ambient noise auto-correlation.The results show notable annual and semi-annual variations,with peak amplitude of±0.8％in 0.1～0.2 Hz(most sensitive to medium at depth of～7 km)gradually decreasing to±0.05％in 1.0～2.0 Hz(to medium shallower than 1 km).The periodic fluctuations of dt/ts may be influenced by seasonal noise source variations,but they exhibit more direct correlation with rainfall and climate temperature apparently.The pore pressure variation induced by precipitation may have a significant impact on both semi-annual and annual cycles.On the other hand,thermodynamic deformation caused by temperature fluctuation only has an obvious annual effect on the medium within a specific depth range(most sensitive to 3 km).The dt/ts change asynchronously with different amplitudes across the four frequency bands,which may be attributed to their sensitive kernel depth ranges and the penetration and propagation process of water and thermodynamic deformation from the surface to the deeper layers.This study highlights the substantial environmental influences on seismic wave traveltimes,and discriminating their individual contributions will help us to accurately assess the changes from the tectonic stress or the human-ecological environments.

Single station ambient noise interferometryTraveltime seasonal changesEnvironmental factorsPore pressure fluctuationsThermodynamic deformation

寇华东、王伟君、闫坤、彭菲、叶志鹏、吕恒茹、常利军

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中国地震局地球物理研究所,北京 100081

中国地震局地震预测研究所,北京 100036

单台背景噪声干涉 走时周期性变化 环境因素 孔隙压变化 热力学形变

中国地震局地震预测研究所基本科研业务费专项中国地震局地震预测研究所基本科研业务费专项中国地震局地震预测研究所基本科研业务费专项中国地震局地震预测研究所基本科研业务费专项国家自然科学基金国家自然科学基金

2020IEF10012020IEF0602CEAIEF20220302022020IEF05044157405041674058

2024

10.6038/cjg2023Q0538

地球物理学报
中国地球物理学会 中国科学院地质与地球物理研究所

地球物理学报

CSTPCD北大核心
影响因子：3.703
ISSN：0001-5733
年,卷(期)：2024.67(4)
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