Geography of Indonesia - Wikipedia

Geography of IndonesiaContinentAsiaRegionSoutheast AsiaCoordinates5°00′00″S 120°00′00″E / 5.000°S 120.000°EAreaRanked 14th • Total8,063,601 km2 (3,113,374 sq mi) • Land23.62% • Water76.38%Coastline54,720 km (34,000 mi)BordersMalaysia: 2,019 km (1,255 mi)Papua New Guinea: 824 km (512 mi)East Timor: 253 km (157 mi)Highest pointPuncak Jaya (Carstensz Pyramid)4,884 m (16,024 ft)Lowest pointSea level0 m (0 ft)Longest riverKapuas River1,143 km (710 mi)Largest lakeLake Toba1,130 km2 (436 sq mi)ClimateMostly tropical rainforest (Af), Southeastern part is predominantly tropical savanna (Aw), while some parts of Java and Sulawesi are tropical monsoon (Am)TerrainPlain in most part of Kalimantan, southern New Guinea, eastern Sumatra and northern Java; Rugged, volcanic topography in Sulawesi, western Sumatra, southern Java, Lesser Sunda Islands and Maluku Islands; Rugged mountains in central, northwestern New Guinea and northern KalimantanNatural resourcesArable land, coal, petroleum, natural gas, timber, copper, lead, phosphates, uranium, bauxite, gold, iron, mercury, nickel, silverNatural hazardsTsunamis; volcanoes; earthquake activity except in central part; tropical cyclones along the Indian coasts; mud slides in Java; floodingEnvironmental issuesSevere deforestation, air pollution resulting in acid rain, river pollutionExclusive economic zone6,159,032 km2 (2,378,016 sq mi)

Indonesia is an archipelagic country located in Southeast Asia, lying between the Indian Ocean and the Pacific Ocean. It is located in a strategic location astride or along major sea lanes connecting East Asia, South Asia and Oceania. Indonesia is the largest archipelago in the world.[1] Indonesia's various regional cultures have been shaped—although not specifically determined—by centuries of complex interactions with its physical environment.Overview[edit]

Indonesia is an archipelagic country extending about 5,120 kilometres (3,181 mi) from east to west and 1,760 kilometres (1,094 mi) from north to south.[2] According to a geospatial survey conducted between 2007 and 2010 by National Coordinating Agency for Survey and Mapping (Bakosurtanal), Indonesia has 13,466 islands.[3] 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.[4] 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 permanent. 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 New Guinea is shared with Papua New Guinea.

Indonesia has total land area of 1,904,569 square kilometres (735,358 sq mi), Including 93,000 square kilometres (35,908 sq mi) of inland seas (straits, bays, and other bodies of water). This makes it the largest island country in the world.[1] The additional surrounding sea areas bring Indonesia's generally recognised territory (land and sea) to about 5 million km2. The government claims an exclusive economic zone of 6,159,032 km2 (2,378,016 sq mi). This brings the total area to about 7.9 million km2.[5][6]

Indonesia is a transcontinental country, where its territory consisted of islands geologically considered as part of either Asia or Australia. During the Pleistocene, the Greater Sunda Islands were connected to the Asian mainland while New Guinea was connected to Australia.[7][8] Karimata Strait, Java Sea and Arafura Sea were formed as the sea level rose at the end of the Pleistocene.Geology[edit]

The tectonic plates & movements under Indonesia

The main islands of Sumatra, Java, Madura, and Kalimantan lie on the Sunda Plate and geographers have conventionally grouped them, (along with Sulawesi), as the Greater Sunda Islands. At Indonesia's eastern extremity is western New Guinea, which lies on the Australian Plate. Sea depths in the Sunda and Sahul shelves average 300 metres (984 ft) or less. Between these two shelves lie Sulawesi, Nusa Tenggara (also known as the Lesser Sunda Islands), and the Maluku Islands (or the Moluccas), which form a second island group with deep, surrounding seas down to 4,500 metres (14,764 ft) in depth. The term "Outer Islands" is used inconsistently by various writers but it is usually taken to mean those islands other than Java and Madura.

Sulawesi is an island lies on three separate plates, the Banda Sea Plate, Molucca Sea Plate, and Sunda Plate. Seismic and volcanic activities are high on its northeastern part, evidenced by the formation of volcanoes in North Sulawesi and island arcs such as the Sangihe and Talaud Islands, southwest of the Philippine Trench.[9][10][11]

Nusa Tenggara or Lesser Sunda Islands consists of two strings of islands stretching eastward from Bali toward southern Maluku. The inner arc of Nusa Tenggara is a continuation of the Alpide belt chain of mountains and volcanoes extending from Sumatra through Java, Bali, and Flores, and trailing off in the volcanic Banda Islands, which along with the Kai Islands and the Tanimbar Islands and other small islands in the Banda Sea are typical examples of the Wallacea mixture of Asian and Australasian plant and animal life.[12] The outer arc of Nusa Tenggara is a geological extension of the chain of islands west of Sumatra that includes Nias, Mentawai, and Enggano. This chain resurfaces in Nusa Tenggara in the ruggedly mountainous islands of Sumba and Timor.

The Maluku Islands (or Moluccas) are geologically among the most complex of the Indonesian islands, consisted of four different tectonic plates. They are located in the northeast sector of the archipelago, bounded by the Philippine Sea to the north, Papua to the east, and Nusa Tenggara to the southwest. The largest of these islands include Halmahera, Seram and Buru, all of which rise steeply out of very deep seas and have unique Wallacea vegetation.[13] This abrupt relief pattern from sea to high mountains means that there are very few level coastal plains. To the south lies the Banda Sea. The convergence between the Banda Sea Plate and Australian Plate created a chain of volcanic islands called the Banda Arc.[14][15] The sea also contains the Weber Deep, one of the deepest point in Indonesia.[16][17]

Geomorphologists believe that the island of New Guinea is part of the Australian continent, both lies on Sahul Shelf and once joined via a land bridge during the Last glacial period.[18][19] The tectonic movement of the Australian Plate created towering, snowcapped mountain peaks lining the island's central east–west spine and hot, humid alluvial plains along the coasts.[20] The New Guinea Highlands range some 650 kilometres (404 mi) east to west along the island, forming a mountainous spine between the northern and southern portion of the island. Due to its tectonic movement, New Guinea experienced many earthquakes and tsunamis, especially in its northern and western part.[21][22]Tectonism and volcanism[edit]

Most of the larger islands are mountainous, with peaks ranging between 2,000 and 3,800 metres (6,562 and 12,467 ft) meters above sea level in Sumatra, Java, Bali, Lombok, Sulawesi, and Seram.[23] The country's tallest mountains are located in the Jayawijaya Mountains and the Sudirman Range in Papua. The highest peak, Puncak Jaya (4,884 metres (16,024 ft)), is located in the Sudirman Mountains. A string of volcanoes stretches from Sumatra to Nusa Tenggara,[24] and then loops around through to the Banda Islands of Maluku to northeastern Sulawesi. Of the 400 volcanoes, approximately 150 are active.[25] Two of the most violent volcanic eruptions in modern times occurred in Indonesia; in 1815 Mount Tambora in Sumbawa erupted killing 92,000 and in 1883, Krakatau, erupted killing 36,000. While volcanic ashes resulted from eruption has positive effects for the fertility of the surrounding soils, it also makes agricultural conditions unpredictable in some areas.