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