The phenomenon of “fluid venting” is globally recognized across various geodynamic contexts, leading to diverse surface morphologies such as pockmarks and mud volcanoes, as well as a range of geological, geochemical, and biological phenomena. Fluid venting involves the upward migration of fluids (including gas) due to subsurface overpressure and/or buoyancy through plumbing systems that are not yet fully understood. Sedimentary layers and geological structures (faults, fractures) can either facilitate or block fluid migration. Fluid seepage in shallow subsurface, increasing pore pressure in sediments, modifies the slope stability leading to landslides and, mutually, the presence of mass-transport deposits influences the location and morphology of fluid venting features.
Two main types of fluid vents are commonly distinguished: (i) “cold seeps,” which are characterized by low-temperature fluid emissions, and (ii) hydrothermal vents, where fluids emerge at temperatures between 200-400°C. In submarine settings, marine geophysical data of different bandwidths can be used to identify fluid-related features on the seafloor and the presence of gas in the water column, which appears as acoustic flares, and below the seafloor, as acoustic anomalies. These anomalies include focused or diffused acoustic turbidity and blanking, bright spots, high-amplitude reflections, chimney or pipe structures, and bottom simulating reflectors (BSRs) associated with gas hydrate.
Sampling and direct observation are also essential for assessing the chemosynthetic ecosystems thriving in these extreme environmental conditions. This session aims to explore the role of submarine fluid flow and venting in: (i) shaping the seafloor as a geomorphic process, (ii) driving other geological processes (i.e. slope instability) (iii) posing potential marine geohazards, and (iv) driving biological processes. Contributions are invited from any offshore region, ranging from continental shelves to abyssal plains, based on multi-scale datasets including hydro-acoustic imagery, 2D/3D seismic reflection data, samples, and ROV observations.