Abstract：Conventional first-arrival travel time tomography based on iterative inversion is computationally intensive and time consuming,especially in a large-scale data processing.In order to improve the efficiency of near-surface modeling,a fast near-surface model building with turning wave is developed by assuming that the near-surface velocity is transversely constant within the maximum offset range and varies linearly with the depth.In order to improve the accuracy of inversion,a multi-datum correction method is adopted to reduce the influence of surface undulation on the inversion results.In order to enhance the stability of inversion,a local weighted ray parameter estimation is developed to increase the robustness with respect to noise.Synthetic and real data tests verify the validity and efficiency of the proposed method.
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