Evaluating Lithospheric Velocity Models in the Sichuan–Yunnan Region of China with Full-Waveform Simulations

Abstract The Sichuan–Yunnan region of China is tectonically active with frequent natural disasters, and where the China seismic experimental site is located. High-resolution seismic lithospheric velocity models are essential for the study of complex lithospheric structures and destructive earthquakes. Although there is an increasing number of velocity models in this region, discrepancies in their absolute values and variation patterns exist. There is also a lack of independent systematic verification and comparison of their accuracy and resolution. In this study, we assessed four recent and representative models by generating synthetic seismograms through full-waveform simulations and comparing time windows of Rayleigh waves against observations from regional earthquakes and ambient noise cross-correlations. The models were quantitatively evaluated through metrics, including travel-time shifts, slowness perturbations, correlation coefficients, and travel-time misfits. Although all models performed relatively well for periods above 20 s, three of four models tend to predict longer travel times than observations, and one shows scattered results. The models exhibit larger velocity biases and worse waveform fits for shorter periods, indicating a lack of resolution in shallow structures and small-scale heterogeneity. Anomalies near major tectonic structures also reflect the deficiency of the models. Our comparative analysis evaluates the reliability of these models across varying frequency ranges and locations. It aids the interpretation of the models and guides their application, particularly in further model refinement, such as initial model selection and identification of specific aspects that require particular attention.