The Stability Zone of Gas Hydrate on the Slope of the East China Sea and Adjacent Trough Basin Area

Abstract

AbstractWe analyze distribution of temperature and heat flow of the sea floor sediment on the East China Sea slope and adjacent West basin area of Okinawa Trough. Based on the Sonar Buoy and Ocean Bottom Seismometer (OBS) data, 6 velocity layers are recognized, each of them has velocity of 1.8 km/s, 2.2(2.0~2.5) km/s, 2.8(2.7~3.2) km/s, 3.4~3.6 km/s, 4.2(4.1~4.7) km/s, and 5.1 km/s, respectively. The upper velocity layer of 1.8~2.2 km/s corresponds to the Quaternary sediment layer, and the layer with velocity 3.4~4.2 km/s is Pliocene sediment layer. The area that is suitable for gas hydrate stable exit area is 70 000km2 which is about 1/10 the total area of East China Sea. The thickness of the stability zone varies from 400m in the middle part of Okinawa Trough to 1 100m in the north and south parts of Okinawa Trough. Quaternary and Pliocene layers are suitable for the stable exitence of gas hydrate. According to the tectonic stability and heat flow, the north and south parts of Okinawa Trough are the most perspective areas for the gas hydrate exploration.