Extraction of Mantle Discontinuities From Teleseismic Body‐Wave Microseisms

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 are migrated 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 a significant step toward body‐wave exploration considering the sources of P‐wave microseisms to be isolated events.

On the Stability of Mantle‐Sensitive P‐Wave Interference During a Secondary Microseismic Event

“…Both Nishida and Takagi (2022) and Zhang et al (2023) provide catalogs of events radiating significant P-waves in the secondary microseismic period band (3-10 s). The receiver-function imaging study in Japan by Kato and Nishida (2023) recently showed such a catalog's value for imaging applications. We decided to probe a "weather bomb", which occurred in southern Greenland from 8 to 11 December 2014.…”