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
Ryukyu Trench km/s, 3.5 km/s, and 4.5–5 km/s. In the area of this transect, the wedge reaches a thickness of 9 km at 50 km from the trench. Beneath the wedge are several seismic layers within the oceanic crust. Separate ocean bottom seismography and multi-channel seismic studies provide insight into the structure of the northern end of the Ryukyu trench region. Features of note include a thick (7–12 km) low velocity (4–5 km/s) zone on the landward side of the trench, the existence of subducting paleo-arc crust near the top of the trench in contrast to simple oceanic crust located at the