Abstract
Love-wave propagation has been a topic of interest to crustal, earthquake, and engineering seismologists for many years because it is independent of Poisson’s ratio and more sensitive to shear (S)-wave velocity changes and layer thickness changes than are Rayleigh waves. It is well known that Love-wave generation requires the existence of a low S-wave velocity layer in a multilayered earth model. In order to study numerically the propagation of Love waves in a layered earth model and dispersion characteristics for near-surface applications, we simulate high-frequency (>5 Hz) Love waves by the staggered-grid finite-difference (FD) method. The air–earth boundary (the shear stress above the free surface) is treated using the stress-imaging technique. We use a two-layer model to demonstrate the accuracy of the staggered-grid modeling scheme. We also simulate four-layer models including a low-velocity layer (LVL) or a high-velocity layer (HVL) to analyze dispersive energy characteristics for near-surface applications. Results demonstrate that: (1) the staggered-grid FD code and stress-imaging technique are suitable for treating the free-surface boundary conditions for Love-wave modeling, (2) Love-wave inversion should be treated with extra care when a LVL exists because of a lack of LVL information in dispersions aggravating uncertainties in the inversion procedure, and (3) energy of high modes in a low-frequency range is very weak, so that it is difficult to estimate the cutoff frequency accurately, and “mode-crossing” occurs between the second higher and third higher modes when a HVL exists.








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Acknowledgments
This work is supported by the National Science Foundation of China (NSFC, #40904031) and the Special Fund for Basic Scientific Research of Central Colleges, China University of Geosciences (Wuhan) (#090106). The first author appreciates the Kansas Geological Survey, University of Kansas, for providing opportunities in surface-wave research and the China University of Geosciences for the financial support to conduct this study. The authors thank Marla Adkins-Heljeson of the Kansas Geological Survey for editing the manuscript.
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Luo, Y., Xia, J., Xu, Y. et al. Finite-Difference Modeling and Dispersion Analysis of High-Frequency Love Waves for Near-Surface Applications. Pure Appl. Geophys. 167, 1525–1536 (2010). https://doi.org/10.1007/s00024-010-0144-7
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DOI: https://doi.org/10.1007/s00024-010-0144-7