Effect of near‐surface anisotropy on a deep anisotropic target layer

Summary Near-surface anisotropy can distort P-wave traveltime and amplitude analysis from deep target layers. When the target layer is azimuthally anisotropic, the traveltime/velocity variation with azimuth (VVAZ) or amplitude variation with azimuth (AVAZ) from the target layer may show anomalous behavior due to the influence of the near-surface anisotropy. This study uses two synthetic cases to analyze the effect of near-surface anisotropy on a deep anisotropic target. Our results suggest that the traveltime data (or VVAZ signals) from the target layers can be distorted significantly due to the presence of near-surface anisotropy; but the near-surface anisotropy influence may be negligible on the AVAZ signals from the deep target layer.