The marine gravity field derived from satellite-altimetry is generally biased, in coastal areas, by signals back-scattered from the nearby land. As a result, the derived gravity anomalies are mostly unreliable for geophysical and geological interpretations of near-shore environments.
To quantify the errors generated by the land-reflected reflections and to verify the goodness of the geologic models inferred from gravity, we compared two different altimetry models with sea-bottom gravity measurements acquired along the Italian coasts.
We focused on the Gulf of Manfredonia, in the SE sector of the Adriatic Sea, where: (i) two different sea-bottom gravity surveys have been conducted over the years, (ii) the bathymetry is particularly flat, and (iii) seismic data revealed a prominent carbonate ridge covered by hundreds meters of Oligocene-Quaternary sediments.
Gravity field derivatives have been used to enhance both (i) deep geological contacts and (ii) coastal noise. The analyses outlined a ringing-noise compromising the altimeter signals up to 17 km from coasts.
Differences between observed data and gravity calculated from a geological model constrained by seismic data, showed that all investigated datasets register approximately the same patterns, associated with the Gondola Fault Zone.
This study showed the potential for implementing gravity anomalies derived from satellite-altimetry with high resolution near-shore data, such as the sea-bottom gravity network available around the Italian coasts. This type of analysis may find future applications to better investigate connections between marine and inland geology in transitional areas.