Extracting Reliable P-Wave Reflections From Teleseismic P Wave Coda Autocorrelation

Recently, many studies have demonstrated the use of teleseismic P wave coda autocorrelation for imaging lithosphere structures. However, the reliability of the extracted reflections remains uncertain and a means of evaluation is lacking. In this study, we propose a velocity analysis method that conveniently solves this problem in place of a synthetic experiment. This method considers the average velocity used for the moveout correction as an unknown quantity and then uses a continuously varying average velocity for the moveout correction. Finally, this method obtains a stacked result that varies with the average velocity and the vertical two-way travel time to produce a v(a)-t(0) diagram. This method is similar to the velocity analysis method used in exploration seismology. In this diagram, reliable reflections correspond to focused energy clusters, while noise lacks this feature. Therefore, this method helps determine which reflections are reliable, while also finding the appropriate parameters for data processing. Synthetic data tests demonstrate the validity of this method as well as a test of field data for station BOSA in the Kaapvaal craton, South Africa, which illustrates the successful application of the method in the case of a sharp and flat Moho discontinuity. Finally, we applied the method to the NCISP-6 dense array and observed obvious energy clusters, representing reflections from the Moho discontinuity in the results for most stations. The depth and shape of the Moho discontinuity determined by this test are consistent with receiver function results, which verify the robustness of this method in relatively complex applications. Plain Language Summary Extracting reflection signals using seismic wave interferometry can reveal important discontinuity structures of the Earth. However, the reliability of the extracted reflections contains large uncertainties and may lead to misleading interpretations. Inspired by the velocity analysis method in exploration seismology, we developed a method that can distinguish reliable reflections and artifacts based on the focus of energy. In turn, this helps us to extract reliable reflections and interpret lithospheric structures. Used with more and more dense array observational data, the proposed method provides a more reliable way to discover the deep complex structures of the Earth and study the evolution of the Earth.