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 Paramush ir Island (Sea of Okhotsk) reveal a local complex structure and an int eresting, unusual pattern of the bottom simulating reflector (BSR). Th e BSR is gradual rising towards the venting area. The geothermal gradi ent and the bottom temperature confirmed the methane hydrate. The temp erature appears to be the most important factor controlling the hydrat e stability. A locally higher heat flow caused the upward migration of the hydrate stability held and the subsequent degradation of the hydr ated sediments, causing gas vent formation and the flux of methane gas into the water column.