Likely P‐to‐S Conversion at the Core‐Mantle Boundary Extracted From Array Processing of Noise Records

Abstract

Seismic noise has been widely used to image Earth's structure in the past decades as a powerful supplement to earthquake signals. Although the seismic noise field contains both surface‐wave and body‐wave components, most previous studies have focused on surface waves due to their large amplitudes. Here, we use array analyses to identify body‐wave noise traveling as PKP waves. We find that by cross‐correlating the array‐stacked horizontal‐ and vertical‐component data in the time windows containing the PKP noise signals, we extract a phase likely representing PKS‐PKP, the differential phase between PKS and PKP. This phase can potentially be used for shear‐wave‐splitting analysis. Our results also suggest that the sources of body‐wave noise are extremely heterogeneous in both space and time, which should be accounted for in future studies using body‐wave noise to image Earth structure.

Extraction of Mantle Discontinuities From Teleseismic Body‐Wave Microseisms

“…Such studies showed that for estimating seismic structures using P‐wave microseisms, considering their source locations is important. Back projection before cross‐correlation is one of the possible solutions for improved extraction (e.g., Liu & Shearer, 2022).…”

Extraction of mantle discontinuities from teleseismic ambient noise

“…Such studies showed that for estimating seismic structures using P-wave microseisms, considering their source locations is important. Back projection before cross-correlation is one of the possible solutions for improved extraction (e.g., Liu & Shearer, 2022).…”