Pacific ring of fire and indonesia

Sumatra (also spelled Sumatera) is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia (two larger islands, Borneo and New Guinea, are partially in Indonesia), and the sixth largest island in the world (approximately 470,000 km²).Sumatra was known in ancient times by the Sanskrit names of Swarnadwīpa ("Island of Gold") and Swarnabhūmi ("Land of Gold"), due likely to the gold deposits of the island's highlands.Arab geographers referred to the island as Lamri (Lamuri, Lambri or Ramni) in the 10-13th centuries, in reference to a kingdom near modern day Banda Aceh which was the first landfall for traders. Late in the 14th century the name Sumatra became popular, in reference to the kingdom of Samudra which was a rising power. European writers in the 19th century found that the indigenous inhabitants did not have a name for the island.

Java (Indonesian: Jawa) is an island of Indonesia and the site of its capital city, Jakarta. Once the centre of powerful Hindu kingdoms, Islamic sultanates, and the core of the colonial Dutch East Indies, Java now plays a dominant role in the economic and political life of Indonesia. Home to a population of 130 million in 2006, it is the most populous island in the world, ahead of Honshū, the main island of Japan. Java is also one of the most densely populated regions on Earth. 

_________________________________________________________________________________

pacific ring of fire is a so active because the large pacific plate is colliding and subsiding with other plates in the area

Other features of the ring are

1. The shrinking of pacific plate as it being older and heavier is subducting and consequently it is shrinking while the atlantic plate is growing.
2. The islands of borneo java sumatra are volacnic in origin
3 san adreas fault of transform boundary are part of it