Abstract

Ocean swell activities excite body-wave microseisms that contain information on the Earth's internal structure. Although seismic interferometry is feasible for exploring structures, it faces the problem of spurious phases stemming from an inhomogeneous source distribution. This paper proposes a new method for inferring seismic discontinuity structures beneath receivers using body-wave microseisms. This method considers the excitation sources of body-wave microseisms to be spatially localized and persistent over time. To detect the P-s conversion beneath the receivers, we generalize the receiver function analysis for earthquakes to body-wave microseisms. The resultant receiver functions migrate to the depth section. The detected 410- and 660-km mantle discontinuities are consistent with the results obtained using earthquakes, thereby demonstrating the feasibility of our method for exploring deep-earth interiors. This study is the first step toward body-wave exploration while considering the sources of P-wave microseisms to be isolated events.