Active Tectonic of Sunda Arc, Indonesia

Sumatra and Java which are part of Indonesia locate eastern and northern of the Sunda Arc. In this topography map which is taken from Jules Verne Voyager (Unavco Facility), we can see clearly that Sumatra and Java lie in the northern part of Indian Ocean (dark blue ~ show how deep is the ocean) and between those islands and the ocean there is a curvature line indicate that there is a subduction zone there(click on 'tectonic' bar on the side column for details). Both island presented in color dark green to light brown. Rough texture and light yellow represent area which is mountainous and high altitude (many volcanoes in this area; click on 'volcanoes'  bar on the left side column for detail.)