瑞雷波频散曲线的分模态提取与联合反演

瑞雷波在层状介质中传播具有频散特性,利用地震记录中的面波信息,提取面波的频散曲线,反演可以建立近地表的横波速度结构模型.本文建立了一个理论地质模型,理论合成面波地震记录,研究了频率波数域中而波频散曲线的分模态提取,并利用等厚分层阻尼最小二乘反演方法对面波各模态的频散曲线进行了分模态反演和联合反演.反演结果表明:瑞雷波基阶频散曲线的浅层(＜10m)反演结果与理论模型吻合最好,一阶高阶频散曲线在15～30m的反演结果与理论模型吻合最好,联合反演在整个深度范围内都可以很好的吻合理论模型,且反演结果的相对误差要低于分模态反演.

Sub-mode Extraction and Joint Inversion of Rayleigh-wave Dispersion Curves

Rayleigh-wave has dispersion properties while travelling in layered media,so we can estimate near-surface S-wave velocities model by inverting the Rayleigh-wave dispersion curve extracted from the Rayleigh-wave information in seismic record.In this paper,we established a theoretical geological model,and synthesized a Rayleigh-wave seismic record.Then we studied the sub-mode extraction of Rayleigh-wave dispersion curves in frequency-wavenumber domain,and inverted Rayleigh-wave dispersion curves using sub-model inversion and joint inversion with the equal thinner layers damped least squares inversion method.The inversion results demonstrate: the fundamental mode dispersion curve inversion result is consistent best with the theoretical result in shallow layers(<10m);the first higher mode dispersion curve inversion result consistent best with the theoretical result is in 15-30m layers;the joint inversion result is consistent well with the theoretical result in all layers,and the relative error of inversion result is lower than that of the sub-mode inversion.