基阶和高阶瑞雷波频散曲线反演对比分析

通过瑞雷波频散曲线反演,可以建立近地表横波速度模型。瑞雷波频散曲线具有多个模态,一般情况下,基阶模态是具有最大能量的模态。目前对瑞雷波频散曲线的反演大多数是基于基阶模态,对于高阶模态的反演比较少。通过对基阶和高阶瑞雷波频散曲线反演对比分析,认为高阶模态和基阶模态频散曲线反演有比较好的一致性趋势,相对而言高阶模态频散曲线反演的横波速度比基阶要高;高阶和基阶模态能量加权反演,不仅保留了频散曲线基阶模态能量强,勘探深度深的特点,而且对浅层低速层也具有更好的响应,可有效提高反演的精度。

Comparative Analysis of Fundamental and Higher-order Modes Rayleigh Wave Dispersion Curve Inversion

Through Rayleigh wave dispersion curve inversion, near-surface S-wave velocity model can be constructed. Rayleigh-wave dispersion curves have several modes and the fundamental mode usually has more energy than any higher-order modes. At present, inversion of fundamental mode dispersion curves is more popular than inversion of higher-order mode dispersion curves. In this paper, the two kinds of inversions are comparatively analyzed, and one conclusion is obtained that the two kinds of inversions are similar. Relatively, S-wave velocity from higher-order mode dispersion curve inversion is higher than that from fundamental mode. Energy weighted inversions of both fundamental and higher-order modes can not only retain dispersion curve with more energy for deeper exploration depth, but also have better responses from shallow low velocity layers, and improving inversion accuracy effectively.