Seafloor features associated with gas hydrate system offshore Coyhaique(Chile)

Seafloor morphologies associated with gas hydrate systems provide important evidence of fluid circulation， gas migration and potential geological instability along continental margins. This study investigates a sector offshore Coyhaique， southern Chile， where seismic and bathymetric data reveal positive seafloor reliefs potentially linked to gas hydrate dynamics. We analyse multichannel seismic reflection data， sub-bottom profiler information and multibeam bathymetry from the MGL1701 expedition， integrating pre-stack depth migration， seismic velocity modelling， gas-phase concentration estimates and sweetness attributes. The results reveal five main seafloor features and two buried features along the analysed seismic profile. One is interpreted as gas hydrate pingo because it displays positive relief， high seismic velocities， low sweetness values， and relatively high gas hydrate concentrations. A second feature is interpreted as a mud volcano， based on its low seismic velocity and high sweetness. The remaining three features cannot clearly be classified as either pingos or mud volcanoes. The two buried features are interpreted as mud volcanoes. These features indicate a geologically complex sector characterised by significant fluid circulation associated with fractures and faults. Finally， the results suggest that this gas hydrate system may be locally unstable， with implications for methane release， geohazards and long-term monitoring of the Chilean continental margin.