GEOLOGY

Detailed explanation-1: -The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian and the Australian plates approximately 43 million years ago.

Detailed explanation-2: -This plate boundary is called the Sumatran Subduction Trench, and it is where the oceanic Indian/Australian plate is slowly descending beneath (subducting under) the continental Eurasian plate at a rate of about 4.5 cm/year (2 inches/year).

Detailed explanation-3: -The Australian plate is a continental plate and the Pacific plate is an oceanic plate. At this boundary, the Pacific plate is slowly moving under the Australian plate. This process is called subduction.

Detailed explanation-4: -Some plates are large enough to consist of both continental and oceanic crustal portions (e.g. the African or South American plates) whilst the Pacific Plate is almost entirely oceanic.

Detailed explanation-5: -Most plates are made of both oceanic and continental crust. An exception is the Pacific plate, which is nearly all oceanic crust. Oceanic crust (basaltic) is thinner and denser than thick and buoyant continental (granitic) crust.