Multichannel analysis of Love waves (MALW) analyzes high-frequency Love waves to determine near-surface S-wave velocities, and it is getting increasing attention in the near-surface geophysics and geotechnique community. Based on 2D geometry spread, in which sources and receivers are placed along the same line, current MALW fails to work in a 3D seismic acquisition system. This is because Love-wave particle motion direction is perpendicular to its propagation direction, which makes it difficult to record a Love-wave signal in 3D geometries. We have developed a method to perform MALW with data acquired in 3D geometry. We recorded two orthogonal horizontal components (inline and crossline components) at each receiver point at the same time. By transforming the raw data from rectangular coordinates (inline and crossline components) to radial-transverse coordinates (radial and transverse components), we recovered Love-wave data along the transverse direction at each receiver point. To achieve a Love-wave dispersion curve, the recovered Love-wave data were first transformed into a conventional receiver offset domain, and then transformed into the frequency-velocity (f-v) domain. Love-wave dispersion curves were picked along the continuous dispersive energy peaks in the f-v domain. The validity of our proposed method was verified by two synthetic tests and a real-world example.

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