  Advances in the field of seismic interferometry have provided a basic
theoretical interpretation to the full spectrum of the microtremor
horizontal-to-vertical spectral ratio [H/V(f)]. The interpretation has been
applied to ambient seismic noise data recorded both at the surface and at
depth. The new algorithm, based on the diffuse wavefield assumption, has been
used in inversion schemes to estimate seismic wave velocity profiles that are
useful input information for engineering and exploration seismology both for
earthquake hazard estimation and to characterize surficial sediments. However,
until now, the developed algorithms are only suitable for on land environments
with no offshore consideration. Here, the microtremor H/V(z, f) modeling is
extended for applications to marine sedimentary environments for a 1D layered
medium. The layer propagator matrix formulation is used for the computation of
the required Green's functions. Therefore, in the presence of a water layer on
top, the propagator matrix for the uppermost layer is defined to account for
the properties of the water column. As an application example we analyze eight
simple canonical layered earth models. Frequencies ranging from 0.2 to 50 Hz
are considered as they cover a broad wavelength interval and aid in practice to
investigate subsurface structures in the depth range from a few meters to a few
hundreds of meters. Results show a marginal variation of 8 percent at most for
the fundamental frequency when a water layer is present. The water layer leads
to variations in H/V peak amplitude of up to 50 percent atop the solid layers.
