Broadband Multi-Aperture Passive Scholte-Wave Imaging Using Seabed Distributed Acoustic Sensing

Shallow-water ocean forcing provides strong broadband passive Scholte-wave illumination along a seabed distributed acoustic sensing cable on the Texas Gulf Coast. We exploit this illumination through direct processing of the uncorrelated wavefield, long-duration frequency-wavenumber stacking, and a multi-aperture strategy that preserves high-frequency spatial localization while resolving low-frequency modes. Constant-wavenumber slices enable spatially consistent multimode tracking across successive array centers. The resulting dispersion spans approximately 0.3-4.5 Hz and supports 400 one-dimensional inversions along a 51-km cable segment. These profiles form a pseudo-2D shear-wave velocity model extending from the near seafloor to approximately 2 km depth. Broad shallow low-velocity intervals are consistent with softer incised-valley fill within stiffer Pleistocene deposits. The results demonstrate that existing seabed fiber infrastructure, when coupled with strong shallow-water passive illumination, can deliver broadband regional shear-wave imaging, while higher-frequency active sources remain necessary to resolve the uppermost several meters.