GAS HYDRATES AND BOTTOM INSTABILITY: BLACK SEA, BULGARIA.

In the continental slope of Bulgarian Exclusive Economic Zone (BEEZ) of the Black Sea, where large volumes of gas hydrates (GH) could be concentrated in sediments near the seafloor, bottom water temperature varies periodically. This for example is due to seasonal changes or can be affected by aperiodic factors. The process of heat transfer from seawater to bottom sediments and thus on gas hydrate and slope stability is modeled. The results of modeling indicate that long time (50 years), seasonal and short-term variations of bottom water temperature may affect gas hydrate stability only in the upper 1-2 m of sediments. However, the zone where repetitive gas hydrate formation and decomposition occur because of bottom water temperature change is extensive in the area with water depths range 300-500 m mainly and up to 1000 m. Examples are shown from new seismic records received in 2011 from the consortium of scientists from all Black Sea countries in the frame of the project BLACK SEA SPAN. [ABSTRACT FROM AUTHOR]