Interpretation of corrected sea floor HVSR data on a gas emitting structure in the Sea of Marmara

Ocean bottom measurements of ambient vibrations at a gas emitting area in the Marmara region are analyzed. It is shown that average horizontal to vertical spectral ratios of seismic noise are weakly affected by oceanic disturbances and can be considered informative about the shallow bottom structure. A procedure is illustrated to account for the peculiar experimental situation and an effective numerical tool is applied to tentatively constrain the local seismostratigraphical configuration by inverting OBS observations. Results of this approach may open new possibilities for a full exploitation of data provided by sea bottom seismic observations to characterize the seabottom sediment structure, in particular in correspondence of gas reservoirs. • H/V spectral ratios of ambient vibrations at the sea bottom are proposed to constrain the subsoil seismic structure. • A procedure is defined to extend the use of inversion tools relative to inland H/V data to ocean bottom observations. • The case of OBS data collected in the Sea of Marmara is examined as a pilot application of the proposed approach. • It is shown that H/V data are weakly affected by the sea dynamics and are representative of the subsoil seismic response. • The inversion of empirical H/V data allows estimating the possible dimension of the gas reservoir in the study area.