The is a seabed feature of the East China Sea

East China Sea

The East China Sea is a marginal sea east of China. It is a part of the Pacific Ocean and covers an area of 1,249,000 km² or 750,000 square miles.-Geography:...

. It is an active, initial back-arc rifting basin which has formed behind the Ryukyu arc-trench system in the West Pacific. It developed where the Philippine Sea Plate is subducting under the Eurasia Plate.

Description

It is a back-arc basin

Back-arc basin

Back-arc basins are geologic features, submarine basins associated with island arcs and subduction zones.They are found at some convergent plate boundaries, presently concentrated in the Western Pacific ocean. Most of them result from tensional forces caused by oceanic trench rollback and the...

 formed by extension within the continental lithosphere behind the far deeper Ryukyu Trench

Ryukyu Trench

The Ryukyu Trench is a 2,250 kilometer long oceanic trench along the southeastern edge of Japan's Ryukyu Islands in the Philippine Sea in the Pacific Ocean. It is located between northeastern Taiwan and southern Japan...

-arc system. It has a large section more than 3,300 feet (1,000 metres) deep and a maximum depth of 8,912 feet (2,716 metres).

The Okinawa Trough still in an early stage of evolving from arc type to back-arc activity.

Interpreting geography

The existence of the Okinawa Trough complicates descriptive issues in the East China Sea. According to Professor Ji Guoxing

Ji Guoxing

Ji Guoxing is a Chinese academic, author, political scientist and professor at Shanghai Jiaotong University.-Career:In 2009, he was Director of Maritime Security Studies Program of the Shanghai Center for RimPac Strategic and International Studies at the Shanghai Institute for International...

 of the Asia-Pacific Department at Shanghai Institute for International Studies

Shanghai International Studies University

Shanghai International Studies University is a research, teaching, and multidisciplinary university based in Shanghai, People's Republic of China. Founded in December 1949 as the former Shanghai Russian School, SISU is one of the top two universities that specialise in studying foreign languages...

,

• China's interpretation of the geography is that
• Japan's interpretation of the geography is that