Sumatra Trench Sumatra Trench The Sumatra Trench belongs to the Sunda Trench or Java Trench. The Sunda subduction zone (called also: the Sumatra-Andaman subduction zone) is located in the east part of Indian Ocean, and is about 300 km from the southwest coast of Sumatra and Java islands. It extends over 5000 km long, starting from Burma in the northwest and ending at Sumba Island in the southeast. The Java trench was generated by the oblique subduction of the Indo-Australian Plate into the Sunda plate at a rate of 61mm/y (in the south) and 51mm/y (in the north). The oceanic crust being
Sumatra Trench to 350 km. The width at Sumatra trench is controlled by sediment input and accretion rate and history. One distinguishing feature of the Sumatra subduction zone is that it has a relatively 120–140 km accretionary prism and a deep forearc basin (so does the rest of the whole Java subduction zone). However it does vary along the trench. The prism is broad and has a relatively shallow surface slope in the northern part, becomes steep and narrow at the central part, then becomes steep and narrow in the southern area. The inner part of the prism forms a NW-SE arc