Seismic fades and specific character of the bottom simulating reflector on the western margin of Paramushir Island, Sea of Okhotsk

Seismic profiles from a venting area on the western margin of Paramushir Island (Sea of Okhotsk) reveal a local complex structure and an interesting, unusual pattern of the bottom simulating reflector (BSR). The BSR is gradual rising towards the venting area. The geothermal gradient and the bottom temperature confirmed the methane hydrate. The temperature appears to be the most important factor controlling the hydrate stability. A locally higher heat flow caused the upward migration of the hydrate stability held and the subsequent degradation of the hydrated sediments, causing gas vent formation and the flux of methane gas into the water column.