Formation of thousands of islands in Indonesian and Philippines

An archipelago (sometimes known as a island group or a island chain) is a chain, cluster or collection of islands. Archipelago may be found isolated in bodies of water or neighbouring a large landmass. Many of them are located in the western Pacific Ocean. Islands in the Indonesian and Philippines Archipelago have been formed due to interactions among Pacific plate, IndoAustralian plate and Philippines plate, converging with each other. 

When the oceanic front of these plates interact with each other, the older and denser plate subducts into a trench, resulting in earthquakes. Sediments of ocean floor and melting of mantle material creates volcanoes at the subduction zone. These volcanoes produce ‘Island arcs’ or group of islands or Archipelago. 

It is the oceanic basaltic floor which, after being metamorphosed, forms the huge series of volcanic arcs (island arcs). In addition of this, tectonic uplifts have also created these islands and mountains on these islands. The overlapping of these areas along ‘Pacific Ring of Fire’ considerably supports the theory of oceanic-oceanic convergence.