Pn‐Wave Receiver Function

Abstract

AbstractThe receiver function (RF) method is the most widely adopted method for imaging crustal structures using earthquake data. Through attenuation during long‐distance propagation, high‐frequency components are scarce in teleseismic waveforms, resulting in low‐frequency RFs and low‐resolution crustal images. The Pn‐wave contains more high‐frequency components because of the short epicentral distance. To improve the resolution of crustal structure studies, we propose the Pn‐wave receiver function (PnRF) method. Unlike other near‐earthquake phases, the Pn‐wave can be considered a plane wave in the crust beneath seismic stations, and interference from other phases can be avoided at epicentral distances of 5–15°. PnRFs calculated from both numerical synthetic data and observational data at broadband seismic stations show that all converted waves are present in PnRFs at the predicted time according to the theory of plane waves. PnRFs calculated by observational data of a dense nodal array clearly show not only the converted wave from the Moho but also the converted wave from the crustal interface, which is too weak to be observed in tele‐RFs because the Pn‐wave has a larger incident angle and higher frequency than the teleseismic P‐wave. When used in conjunction with dense nodal array observations, the PnRF method has the potential to image crustal structures with a high resolution close to that of the deep seismic reflection method.