Joint Autocorrelation and Receiver Function Analysis of Sedimentary Structures Using Strong Ground Motion Records

Joint analysis of the receiver and autocorrelation functions was performed to estimate the structure of the P- and S-wave velocities V P and V S as well as the depth to the seismic bedrock using strong motion records obtained in Narita, Kanto basin, Japan. From data of over 1000 P-waves and their coda induced by local seismic events, the autocorrelation revealed a clear reflection in the sedimentary layer, and the receiver function revealed clear Ps and PpPs converted phases at the seismic bedrock. The sediment thickness and V S were measured from the H – κ stack of the vertical and transverse components of the autocorrelation and the Ps and PpPs phases in the receiver function. The previous V S structure model obtained with only the transverse autocorrelation in Narita was found to be appropriately evaluated, whereas the corresponding V P structure model must be improved. Because the H – κ stack requires an assumed V P value, an appropriate value of V P is crucial for accurate estimation of V S and the thickness of the sediment. Thus, the frequency analysis of the H – κ – V P stack was performed to estimate V P , V S , and the thickness of the sedimentary structure. From the results of this analysis, V S was determined to have been estimated appropriately for the present case in Narita. However, V P had been estimated to be lower than the value estimated by this study. It is clear that an appropriate assumption of V P is important to capture the Ps and PpPs phases in the receiver function.