Full‐waveform inversion of surface waves based on instantaneous‐phase coherency

Abstract

AbstractFull‐waveform inversion of surface waves can provide high‐resolution S‐wave velocity (Vs) of the shallow subsurface and is becoming a popular shallow‐seismic method. We propose a misfit function based on instantaneous‐phase coherency, which can measure the amplitude‐unbiased coherency between measured and synthetic data. The instantaneous‐phase coherency was once the key component that was used in the phase‐weight stacking technology to enhance the weak but coherent signals. Using synthetic data, we show that our full‐waveform inversion approach based on the proposed misfit function is robust in reconstructing subsurface anomalies from data contaminated by random noise. We also show that our misfit function is robust against the errors in the estimated source wavelets. We then choose to use published field data acquired at an archaeological site as a benchmark dataset to test the performance of our full‐waveform inversion in a real environment. Subsurface structures identified in our inversion results are verified by an independent archaeological excavation, while the results from conventional full‐waveform inversion are dominated by artefacts. The results of synthetic tests and field data experiments demonstrate the robustness of our full‐waveform inversion approach in reconstructing the shallow subsurface structure from field data, where amplitude information of recorded wavefield may not be correctly recorded.