| 面波频散谱多模式高分辨率成像的多道信号比较法 |
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| 引用本文： | 易佳,刘伊克,胡昊,张郁山,杨宗奇.面波频散谱多模式高分辨率成像的多道信号比较法[J].地球物理学报,2021,64(5):1710-1720. |
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| 作者姓名： | 易佳 刘伊克 胡昊 张郁山 杨宗奇 |
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| 作者单位： | 中国地震灾害防御中心,北京100029;中国科学院地质与地球物理研究所,北京 100029;University of Houston, Houston Texas, 77204-5007, USA;中国石油集团东方地球物理勘探责任有限公司,河北涿州072750 |
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| 基金项目： | 国家自然科学基金(42004047);国家重点研发计划(2019YFC1509402)联合资助. |
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| 摘 要： | 高分辨率的面波频散谱成像是浅层地震勘探领域基于频散性质反演横波速度结构中的一个关键步骤.在天然地震探测领域,仅利用两个台站记录的线性信号比较法(LSC),被广泛用来计算面波的频散谱,并用于大尺度的面波层析成像.然而互相关的成像方式会造成频散谱在低频端较低的分辨率.非线性信号比较法(NLSC)利用指数函数克服了这个问题,同时极大地提高了频散谱的成像分辨率.然而,在研究中我们发现,仅利用两个台站的地震记录,并不能将面波的频散特性完整地考虑在内,导致LSC和NLSC方法对高阶模式的成像存在较大的误差.由于主动源面波勘探多道采集的方式,基于信号比较理论的多道信号比较法(MSC)充分利用多道地震信号,可以获得准确的多模式成像,然而该方法需要计算任意两道的频散谱并叠加,存在冗余的计算,导致计算效率较低.因此,本研究对MSC方法进行了相应的改进,通过追踪炮集记录上的面波波组提高了原方法的计算效率,同时,利用理论频散曲线进行叠加分析,验证了改进的MSC方法的正确性和有效性.通过与相移法、LSC和NLSC方法的对比分析,展示了MSC方法是一种准确的、高分辨率的面波多模式频散谱成像方法.实际地震资料的应用,揭示了MSC方法在浅层地震勘探中用于提取面波多模式频散信息的巨大潜力.
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| 关 键 词： | 浅层地震勘探 横波速度 面波 频散曲线 信号比较法 |
High-resolution multimode surface-wave dispersion spectrum imaging with a multichannel signal comparison method |
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| YI Jia,LIU YiKe,HU Hao,ZHANG YuShan,YANG ZongQi.High-resolution multimode surface-wave dispersion spectrum imaging with a multichannel signal comparison method[J].Chinese Journal of Geophysics,2021,64(5):1710-1720. |
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| Authors: | YI Jia LIU YiKe HU Hao ZHANG YuShan YANG ZongQi |
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| Affiliation: | (China Earthquake Disaster Prevention Center,Beijing 100029,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Houston,Houston Texas,77204-5007,USA;BGP INC.,CNPC,Zhuozhou Hebei 072750,China) |
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| Abstract: | High-resolution surface-wave dispersion spectrum imaging is crucial for estimating the shallow subsurface S-wave velocity based on the dispersion properties.In global seismic exploration,linear signal comparison(LSC)method is widely used to compute the dispersion spectrum,which uses only two seismic records.However,LSC relies on a cross-correlation strategy that leads to poor resolution in the low-frequency regions.Nonlinear signal comparison(NLSC)approach overcomes the resolution problem and can achieve high-resolution imaging by using the exponential function.However,we find that LSC and NLSC both suffer a severe problem:the higher modes imaging is inaccurate since the dispersion properties are not fully considered by utilizing only two recorded data.Based on the multichannel acquisition system in active source surface wave exploration,multichannel signal comparison(MSC)method takes all the signals into account,which can obtain an accurate multimode dispersion spectrum.However,MSC method needs to compare the signals of every two records that cause the problem of redundant calculation and low efficiency.Therefore,we improve the computational efficiency of MSC method by tracing the surface wave in the shot gathers.By comparing with the theoretical dispersion curves,we verify the effectiveness of the modified MSC method.Through comparing with the phase shift method,LSC,and NLSC,we demonstrate that MSC is a high-resolution and high-precision surface-wave multimode dispersion spectrum imaging approach.The application of field data reveals the great potential of MSC method in extracting multimode surface wave dispersion information in shallow seismic exploration. |
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| Keywords: | Shallow subsurface seismic exploration S-wave velocity Surface-wave Dispersion curve Signal comparison method |
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