Vp and Vs structure estimations from ambient seafloor noise observed by
distributed acoustic sensing
Seismic velocity structures have been estimated using ambient noise
records observed by distributed acoustic sensing (DAS) technology.
Previous studies have obtained S-wave velocity (Vs) structures along
submarine cables using surface waves; however P-wave velocity (Vp)
structure have seldom been constructed because ambient noise primarily
contains surface waves. Here, we show P and Rayleigh wave extractions
from ambient seafloor noise observed by DAS, and also estimate the Vp
and Vs structures along a submarine cable deployed off Cape Muroto in
the Nankai subduction zone, Japan. To extract the P waves, we calculated
the cross-correlation functions (CCFs) of the ambient noise and applied
a frequency-wavenumber filter to the CCFs to remove the effects of
slower surface waves. The results indicate that similar features can be
obtained in the Vp and Vs profiles, and that the P wave extractions can
be performed on days with poor weather conditions.