基阶与高阶瑞利波联合反演研究

研究了六层层状介质模型瑞利波基阶和高模式波相速度对横波速度、深度的敏感性，结果表明：基阶波较高模式波对7 m以内浅部地层的横波速度更敏感，敏感性频带在10～25 Hz范围内，峰值频带集中在18 Hz左右；高模式波较基阶波对深部地层的横波速度更敏感，敏感性频带宽，峰值分散.基阶波对浅层的敏感性和高模式波穿透深度更深的特点为近地表岩土层二维横波速度结构的联合反演提供了前提条件.利用阻尼最小二乘SVD（Singular Value Decomposition）算法联合基阶与高模式波对理论模型和实例数据进行横波速度反演，反演结果表明联合反演增强了反演的稳定性，提高了反演的精度.

Joint inversion of fundamental and higher mode Rayleigh waves

In this paper, we analyze the characteristics of the phase velocity of fundamental and higher mode Rayleigh waves in a six-layer earth model. The results show that fundamental mode is more sensitive to the shear velocities of shallow layers (<7 m) and concentrated in a very narrow band (around 18 Hz) while higher modes are more sensitive to the parameters of relatively deeper layers and distributed over a wider frequency band. These properties provide a foundation of using a multi-mode joint inversion to define S-wave velocity. Inversion results of both synthetic data and a real-world example demonstrate that joint inversion with the damped least squares method and the SVD (Singular Value Decomposition) technique to invert Rayleigh waves of fundamental and higher modes can effectively reduce the ambiguity and improve the accuracy of inverted S-wave velocities.