Sensitivity analysis of multi-mode Rayleigh and Love wave phase-velocity dispersion curves in horizontal layered models
(2.Subsurface Imaging and Sensing Laboratory, China Unversity of Geosciences (Wuhan), Wuhan, Hubei Province, China 430074)
(3.Zhejiang Provincial Institute of Communications Planning, Design & Research CO., LTD., Hangzhou, Zhejiang Province, China 310000)
(4.MOE Key Laboratory of Fundamental Physical Quantities Measurements, Hubei Key Laboratory of Gravitation and Quantum Physics, School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei Province, China 430074)
【Abstract】High-frequency surface-wave method with Rayleigh wave and Love wave as the main study objects is widely applied in various fields such as underground water, environment and engineering. For horizontal layered models, S-wave velocities are the most important parameters for estimating multi-mode Rayleigh wave and Love wave phase-velocity dispersion curves. In this paper, the Jacobian matrix was used to infer the sensitivities of multi-mode Rayleigh wave and Love wave phase-velocity dispersion curves to S-wave velocities of the formations at different depths. The following conclusions were drawn. (1) The sensitivities of surface waves of different modes to the S-wave velocity at a certain depth are different. For both Rayleigh wave and Love wave, low-frequency surface wave is more sensitive to the S-wave velocities in deep formations, compared with high-frequency surface wave. Moreover, multi-mode phase velocities with a broad high-frequency range are sensitive to surface S-wave velocity. (2) Based on a velocity increasing layered model and two layered models with velocity anomalies (containing low-velocity interlayer and high-velocity interlayer), the analysis suggested that the phase-velocity dispersion curves of both Rayleigh wave and Love wave are sensitive to S-wave velocity in low-velocity layer, and they are both not sensitive to the S-wave velocity in high-velocity layer or below velocity anomaly layer (low-velocity layer or high-velocity layer). (3) For surface wave of a certain mode, the frequency band of Love wave, in which phase-velocity dispersion curves are sensitive to S-wave velocity of a specific layer, is wider than that of Rayleigh wave. In addition, the sensitivity peaks of Rayleigh wave and Love wave phase-velocity dispersion curves to S-wave velocity of a certain layer are different. Therefore, joint inversion of multi-mode Rayleigh wave and Love wave phase-velocity dispersion curves can be applied to obtain high-precision shallow subsurface S-wave velocity.
【Keywords】 Rayleigh wave; Love wave; multi-mode; phase-velocity dispersion curves; Jacobian matrix; sensitivity analysis;
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