Geography of Indonesia
Indonesia is an archipelagic country extending about from east to west and from north to south. According to a geospatial survey conducted between 2007 and 2010 by National Coordinating Agency for Survey and Mapping (Bakosurtanal), Indonesia has 13,466 islands. While earlier survey conducted in 2002 by National Institute of Aeronautics and Space (LAPAN) stated Indonesia has 18,307 islands. According to the CIA World Factbook, there are 17,508 islands. The discrepancy between the surveys is likely caused by the earlier different survey method including tidal islands, sandy cays and rocky reefs that surface during low tide and submerge during high tide. There are 8,844 named islands according to estimates made by the government of Indonesia, with 922 of those are permanently inhabited. It comprises five main islands: Sumatra, Java, Borneo (known as "Kalimantan" in Indonesia), Sulawesi, and New Guinea; two major island groups (Nusa Tenggara and the Maluku Islands) and sixty smaller island groups. Four of the islands are shared with other countries: Borneo is shared with Malaysia and Brunei; Sebatik, located off the northeastern coast of Kalimantan, shared with Malaysia; Timor is shared with East Timor; and the newly divided provinces of Papua and West Papua share the island of New Guinea with Papua New Guinea.
Volcanology of Indonesia
Indonesia is a volcanically active country, containing numerous major volcanoes. It has the most volcanoes of any country in the world, with 76 volcanoes that have erupted at least 1,171 total within historical times. The Smithsonian Institution has 141 Indonesian entries in its volcano database. Indonesia has around 130 active volcanoes that are part of the Pacific Ring of Fire, and it has suffered the highest numbers of eruptions resulting in fatalities, damage to arable land, debris flows, tsunamis, lava domes, and pyroclastic flows. Indonesia's most active volcanoes are Kelut and Mount Merapi on the island of Java. The majority of Indonesia's volcano are located on a 3,000 km long chain called the Sunda Arc. Here, the subduction of the Indian Ocean crust underneath the Asian Plate produced most of these volcanoes.