From Orthogonal to Oblique Subduction along the Sunda Margin

Transition from the Eastern part of the Indian Ocean to the Asian continent is a subduction zone evoking great scientific interest. It’s well-known as Sunda trench or Sunda plate boundary.<br>The aforementioned junction is defined as an oblique horizontal convergence of continental and ocean plates. The margin of connecting lithospheric plates changes its strike from latitudinal to meridional (from south to north). North-North-Eastern general movement of Indian-Australian plates (Eurasia plate fixed) leads to the fact that this interconnection affects conditions of subduction. In the south oceanic plate subducts sub-orthogonally, whereas in the area of the Bay of Bengal it is sinking obliquely, close to the tangential direction. At the same time from the south to north the rate of relative movement of adjacent tectonic plates decreases from 76 to 59 mm/yr correspondingly.<br>The Sunda plate boundary along its northern and central part represents a classic accretion. Off central Java, the frontal prism has been eroded and the deformation front shifted northward.<br>Thus, according to the geological parameters and type of convergent margin we divided Sunda subduction zone into three parts: Sector of Central and Eastern Java (South-Eastern), Sector of Sumatra and Western Java (Central), Andaman (Northern) Sector.<br>