Indonesia is located in Southeast Asia between the Pacific Ocean and Indian Ocean. It is an archipelagic country made up five large islands - namely, Java, Sumatra, Sulawesi, New Guinea and Kalimantan. It also has about thirty small archipelagoes such as Maluku and Nusa Tenggara among others.  The country is surrounded by sea as it straddles two continents – Australia and Asia.  It shares four of these main islands with other nations such as Papua New Guinea and Malaysia.  Tropical rainforest, open savanna, and grassland are the main vegetation in Indonesia (AsianInfo.org)..

Indonesia

 

Tectonically, Indonesia is very unstable because it is located between Australian and Eurasian plates. The subduction of plate of Indian Ocean under the Eurasian plate formed a volcanic arc in the west of Indonesia. This volcanic arc is the most active area seismically with powerful earthquakes and volcanic eruptions. The formation of landscapes such as crater lakes, faults and mountains in Indonesia were mainly done through volcanicity and earthquake process. It is the string of these active volcanoes that led to  the formation of Bali, Java, Nusa Tenggara and Sumatra islands. These tectonics processes formed major structures such as the Great Sumatran Fault in Sumatra, Palu-Koro fault in Sulawesi, and Sorong fault in New Guinea.

Tectonic Setting of Sumatra

Topographically, Indonesia mainly consists of coastal lowlands. However, some of the main islands such as Sumatra and Java have interior volcanic mountains with peaks rising to about 3,650 m. Lombok and Bali islands have gently sloping mountainsides and wide lowlands plains. Sulawesi Island is predominated with Mountainous landscape and hilly land with swamp forests dominates Kalimantan Island. The New Guinea Island could be a part of the Australian continent if the tectonic action and breakup did not occur to create a towering snow-capped mountain peaks that lines the central east-west spine of the island. Indonesia records more than 400 volcanoes and about 150 are active volcanoes. (Darman & Sidi, 2000).

An image showing the the mountain peaks

Work cited

AsianInfo.org. Indonesia's Geography (Archipelago, Sumatra, Java/Madura). n.d. 13 09 2014. <http://www.asianinfo.org/asianinfo/indonesia/pro-geography.htm>.

Darman, H. & Sidi, H.  An Outline of the Geology of Indonesia, Indonesian Geologists Association publication, 2000.