Time distortions due to heterogeneity in the near- surface can seriously degrade the quality of migrated reflection seismic data. Using raypath-based kinematics for simple near-surface models, we examine the errors introduced into data by applying vertical-path, static corrections to finite-difference-modeled, unstacked data. We consider two alternative near-surface-correction techniques. The first one, layer replacement, simulates data that would be recorded at the original recording surface with the near-surface, weathered layer replaced by the higher velocity of sub weathering. The second is downward continuation, which aims to simulate data that would be recorded at a datum level below the near- surface layer.

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