Indonesian Geography

Indonesia is an archipelago made up of more than ten thousand islands, of which 8,844 have names and 922 are inhabited. It comprises five main islands: Sumatra, Java, Borneo, Sulawesi and New Guinea, two major island groups: the Lesser Sunda Islands and the Moluccas, and sixty smaller island groups. Four of the islands are shared with other countries: Borneo with Malaysia and Brunei; Sebatik, northwest of Kalimantan, with Malaysia; Timor with East Timor, and the newly divided provinces of Papua and West Papua share the island of New Guinea with Papua New Guinea.

A relatively open expanse of water (formed by the Java, Flores, and Banda seas) divides most of Indonesia's islands into two unequal rows of islands: to the south, the (comparatively long and narrow) islands of Sumatra, Java and Timor among others, and to the north, Borneo, the Celebes Islands, the Moluccan archipelago and New Guinea.

A range of volcanic mountains, reaching altitudes above 3,700m, stretches west to east across the southern islands from Sumatra to Timor. The highest points in this chain are Kerinci (3,800 m) in Sumatra, and Semeru (3,676 m) in Java. Each of the main northern islands has a central mountain mass and plains around the coast. Puncak Jaya (5,030 m), in the Surdiman mountain range of Irian Jaya, is the highest peak in the country. The areas with the largest extension of lowlands are Sumatra, Java, Borneo and Irian Jaya. For centuries periodic volcanic eruptions from the many active volcanoes have deposited rich soils in the lowlands, especially in Java. Many Indonesian volcanoes are still active and earthquakes also occur in the area. One of the most destructive was the 2004 Indian Ocean earthquake, centered near Sumatra, which affected the entire Indian Ocean basin, killing more than 200,000 people.

Geology

Side Plate in Indonesia

The main islands of Sumatra, Java, Madura, and Kalimantan rest on the Sunda Plate and are grouped, along with Sulawesi, into the Greater Sunda Islands. At the eastern end of Indonesia is New Guinea, which lies on the Australian plate. The marine depth on the Sonda and Sahul plates averages 300 m or less. Between these two tectonic plates lie Sulawesi, the Lesser Sunda Islands, and the Moluccas, which form a second group of islands with depths in the surrounding seas of up to 4,500 m. The island of Sulawesi lies on three separate plates, the Banda Sea plate, the Moluccan Sea plate, and the Sunda or Sunda plate. Seismic and volcanic activity is high in the northern part, evidenced by volcanic formations in North Sulawesi Province in North Sulawesi and the island arc including the Sangihe Islands and Talaud Islands, to the southwest of the Philippine trench.

The Lesser Sunda Islands consist of two rows of islands stretching east from Bali toward the southern Moluccas. The inner arc of the Lesser Sunda Islands is the continuation of the alpine belt of mountains and volcanoes that stretches from Sumatra through Java, Sumatra and Flores, and disappears into the volcanic Banda Islands, which, together with the islands Kai, the Tanimbar Islands, and other small islands in the Banda Sea are typical examples of Wallacean mixing of Asian and Australasian plants and animals. The outer arc of the Lesser Sunda Islands is a geological extension of the western island chain. of Sumatra which includes Nias, Mentawai and Enggano. This chain reappears in the lesser Sunda islands in the rugged mountains of the islands of Sumba and Timor.

Tectonic map of the bow of Banda

The Moluccan Islands are geologically one of the most complex of the Indonesian islands, formed by four tectonic plates. They are located in the northeast of the archipelago, surrounded by the Philippine Sea to the north, Papua to the east, and the Lesser Sunda Islands to the southwest. The largest islands, Halmahera, Seram and Buru rise steeply from a deep sea and have unique Wallacea vegetation. There are hardly any coastal plains. To the south is the Banda Sea. The convergence between the Banda Sea plate and the Australian plate creates a volcanic chain called the Banda Arc.

Geomorphologists believe the island of New Guinea is part of the Australian mainland, as the two lie on top of the Sahul plate and were linked by land during the last glacial period. The tectonic movement of the Australian plate has created towering mountains that ridge the center of the island from east to west, and warm floodplains along the coasts. The Cordillera Central runs for 650 km from east to west, forming a spine between the north and south of the island. Due to these movements, New Guinea experiences numerous earthquakes and tsunamis, especially in the northern and northern parts.

Tectonics and volcanism

Most of the large islands are mountainous, with peaks ranging from 2,000 to 3,000 m above sea level in Sumatra, Java, Bali, Lombok, Sulawesi, and Seram. The country's highest peaks are in the Jayawijaya Mountains., in New Guinea, and in the Sudirman Mountains, in Papua. The highest peak, Puncak Jaya, at 4,884 m, is located in the Sudirman Mountains. A row of volcanoes stretches from Sumatra to the Lesser Sunda Islands, and then makes a turn toward the Banda Moluccas Islands, northeast of Sulawesi. Of the 400 volcanoes, about 150 are active. Two of the most violent eruptions in historical times have taken place in Indonesia; in 1815, an eruption on Mount Tambora, in Sumbawa, killed 92,000 people, and in 1883, Krakatoa killed 36,000. While volcanic ash proves to be very positive for agriculture, the risk of eruptions and earthquakes make conditions unpredictable in many areas.

List of volcanoes in Indonesia.

Indonesia has relatively high tectonic and volcanic activity. It lies at the convergence between the Eurasian, Indo-Australian, Pacific and Philippine Sea plates. The Sunda megafault is a 5,500 km long fault located off the southern coasts of Sumatra, Java, and the smaller Sunda islands, where the Indian plate pushes northeastward, subducting the Sunda plate. Tectonic movement on this plate is responsible for the creation of the Sunda or Java Trench and ridges across Sumatra, Java, and the Lesser Sunda Islands. Numerous large earthquakes occur in the vicinity of the fault, such as the 2004 Indian Ocean earthquake. Mount Merapi, located on the Java portion of the megafault, is the most active volcano in Indonesia and is known as one of the Decade Volcanoes, due to the risk it poses to the populated neighboring areas.

Northern Sulawesi and the Moluccan Islands lie at the convergence of the Sunda Plate and the Moluccan Sea Plate, giving rise to an active tectonic region with volcanic chains such as the Sangihe and Talaud Islands. The northern Moluccas and western New Guinea lie at the convergence of the Bird's Head, Philippine Sea, and Caroline Sea plates. It is also an active volcanic region, with the 2009 Papua earthquake of category 7.7 Mw the most recent earthquake in the region.

Natural resources

Bali.

Indonesia's rich volcanic soil is ideal for growing crops; forests extend over its surface and cover approximately two thirds of the territory.

The country's main resources are tin, bauxite, oil, natural gas, copper, nickel and coal; it also has small amounts of silver, diamonds and rubies. Fishing is abundant and pearls, shells (hawksbill) and agar, a substance extracted from algae, are also obtained from the sea.

Climate

Climate map of Indonesia. In dark blue, equatorial; in medium blue, monzonic, and in lighter blue, savannah dry

The warm waters around Indonesia and the fact that it has about a thousand islands along the equator, between Southeast Asia and Australia, with more than 5000 km from west to east, provide a mild and equatorial climate, warm and humid year-round, with thunderstorms or showers sometimes causing flooding. Average temperatures are 28 °C along the coastal plains and 23 to 26 °C in the mountains in the center of the islands. Relative humidity ranges from 70 to 90%. The winds are moderate, the monsoon, in general, blows from the southwest between June and September, and from the northeast between December and March. Typhoons and storms are rarely a danger, inter-island currents are the biggest risk to shipping, especially in the Lombok Strait.

Depending on the place, there is a more or less dry season. The day lasts 12 hours all year long, but in the mountainous areas, which are very cloudy, you hardly see the sun's rays.

Bogor City, with Mount Salak at the bottom.

Rainfall is heaviest on the coast and western slopes of Sumatra, the southern slopes of western Java, most of Borneo (except the southwest), and much of western Western New Guinea. In southwestern Sumatra, about 4,000 mm falls per year, and between October and December, more than 400 mm fall each month. In Padang, the capital of West Sumatra, with an average annual temperature of 27.oC, with highs of 27.5.oC and lows all year of 22.5.oC, with a minimum variation of 1 degree between these variables, drop 4,040 mm, with a minimum of 200 mm in September and 500 mm in November, exceeding 400 mm between October and November.

In Borneo, the weather is also very humid, and it's hard to find a month when less than 250mm falls. However, it is hotter. In Kalimantan they fall between 2,500 and 3,200 mm, but in Pontianak, for example, temperatures range between 32-33.oC mean of the maxima and the 23.oC mean of the minimum

It rains less north of Sumatra, southeast of Borneo, extreme north of Sulawesi, Maluku Islands and the westernmost part of New Guinea, with a subequatorial or tropical savannah climate (according to Köppen(, since there is a part of the year in that do not exceed 100 mm per month. In Banda Aceh, North Sumatra, about 2,000 mm falls per year, with two periods of about 100 mm per month between June and August and February and March. In North Sulawesi, this happens between July and September, but in the Maluku islands, the situation is reversed, with more than 400 mm in those months and around 100 mm from October to February.In the capital of the Moluccas, Ambon, 2,615 mm fall per year, in June and July exceed 400 mm, and between October and February they barely exceed 100 mm.

The driest place in Indonesia, however, is in the southern zone, between Jakarta, the islands of Bali, Komodo and Timor, and southern New Guinea. In Jakarta, north of Java, with temperatures between 24 and 32.oC all year, they fall about 1800 mm, with less than 100 mm between June and September, and a minimum of 45 mm in August. In Bandung, also in Java, but at 700 m altitude, temperatures range between 17 and 28.oC and fall about 2,160 mm per year, with 68 mm in August and 290 mm in December. On the island of Bali, east of Java, about 1,700 mm fall annually, and the rains decrease towards the east: islands of Lombok, Sumbawa, [Komodo Island|Komodo]], Flores, Sumba, fall about 1,300-1,400 mm, and in areas of Sumba, in the north and east, about 800 mm fall, with a dry period from May to November.

On the island of Timor they fall between 1200 and 1500 mm. To the east of Timor, to the south of the Moluccas islands, it rains again and exceeds 2,000 mm, with a dry period from August to October. On the Tanimbar Islands, in the Moluccas, 2,350 mm fall annually, with 50 mm in August and September, and more than 300 mm between December and March. For its part, in Macassar, on the island of Celebes, with 2,875 mm, less than 100 mm falls between June and October, with 14 mm in August, and more than 500 mm between December and February, with almost 700 mm in January. Temperatures, between 23 and 32.oC are very stable.

Volcano chain east of Java, the Semeru and Bromo mountains.

In the chain of volcanoes on the island of Java, which reaches 4,884 m on Mount Jaya, the number of storms increases. In the surroundings of Bogor, nicknamed the 'city of rain' In the vicinity of Mount Salak, at 2,211 m, about 4,000 mm fall per year and the largest number of storms on the planet occurs, up to 322 per year. The rains occur on the north face of the volcano between December and March, and on the south face between June and September, depending on the monsoon. Nine months exceed 300 mm.

Between November and May, cyclones can affect the south of the islands, and between April and December, north of the equator, but the incidence is small. When the El Niño phenomenon occurs, there is a drought between June and August, but it can last until September and even November. La Niña produces a cooling between June and August.

Main islands

The main islands are listed in the following table:

There are also many other islands of minor importance, which by geographical area are:

• Great Sonda Islands

• Cells and attached islands:

• Sangir
• Talaud Islands
• Togian Islands

• Islands attached to Java

• Bawean
• Kangean Islands
• Karimun Jawa

• Islands attached to Sumatra:

• Thousands of Islands
• Enggano
• Riau Islands (Batam, Bintan, Karimun, Lingga Islands, Natuna Islands)
• Simeulue

• Small islands of the Sonda

• Alor Archipelago
• Komodo
• Palu'e
• Roti or Rote
• Solor

• Molucas

• New Guinea

• Biak
• Sorong

Environmental problems

Deforestation in the province of Riau, Sumatra, to replace the forest with a palm oil plantation, 2007.

Active volcano chain in Indonesia from ISS, international space station.

High population and rapid industrialization present serious environmental problems, which are given low priority due to high levels of poverty and a weak and resource-poor government. Problems include large-scale deforestation (much illegal) and related fires causing intense smog in parts of western Indonesia, Malaysia, and Singapore; the overexploitation of marine resources, and the environmental problems associated with rapid urbanization and economic development, including air pollution, traffic congestion, waste and sewage management.

Deforestation and destruction of topsoil make Indonesia the third largest emitter of greenhouse gases. Habitat destruction threatens the survival of indigenous and endemic species, including 140 species of mammals identified by the IUCN as threatened, and 15 identified as critical, including the Sumatran orangutan.

In 1970, 15% of Indonesians lived in cities, compared to 30% today, putting pressure on the urban environment. Industrial pollution is of particular concern in Java, as is the increase in the number of motor vehicles. Very few Indonesians have access to reliable drinking water, and most have to boil their water before drinking it.

Indonesian Protected Areas

According to the IUCN, in Indonesia there are 733 protected areas that occupy some 231,946 km², 12.17% of the territory, in addition to 181,848 km² of marine areas, 3.06% of the 5,947,954 km² that belong to the country. Of these, 49 are national parks, 1 is a marine management area (Kota Batam), 1 is a multiple-use marine reserve (Teluk Ambon), 6 are game reserves, 9 are marine national parks, 1 is a recreational park., 252 are nature reserves, 84 are wildlife reserves, 1 is a protected forest (Gunung Boliyohuto), 21 are recreational marine parks, 4 are coastal parks, 11 are marine nature reserves, 2 are islet coastal parks, 37 are parks in large forests and 1 is a marine culture protection area.

On the other hand, in Indonesia there are 7 UNESCO biosphere reserves, 4 World Heritage Sites and 7 Ramsar sites with a global area of 13,730 km².

Komodo Dragons on Rinca Island, in the Komodo Biosphere Reserve.

Unesco Biosphere Reserves

• Cibodas, in western Java, southwest of Jakarta, 06°40' at 06°50S'; 106°51' at 107°02'E, 57.532 ha, montane forest and humid tropical submone under human pressure, laurel, oak, chestnut, Schima wallichii. It includes the Gunung Gede Pangrango National Park and includes the Cibodas Botanic Garden.

• Komodo, 08°24' at 08°50'S; 129°21' at 129°49'E, 1.733 km2. Between Flores and Sumbawa, it is also Komodo National Park, covers the islands of Komodo, Rinca and Padar and numerous islets. Famous for the dragon of Komodo.

• Tanjung Puting, 02°35' at 03°35'S; 111°45' at 112°15'E, 4.150 km2. On Borneo Island, Kalimantan Central Province. Famous for the conservation of the orangutan of Borneo. Mangroves, coastal and degraded forest.

• Lore Lindu, 01°15' at 01°30'S; 119°50' at 120°20'E, 2.180 km2, in Sulawesi.

• Gunung Leuser, 02°55' at 04°05'N; 96°55' at 98°30'E, 7.927 km2. Rainforest, northern Sumatra.

• Giam Siak Kecil-Bukit Batu (GSK-BB), 7.052 km2. Wetlands and forested peats in Sumatra with rare species. Sumatra Elephant, Sumatra Tiger, Marine Crocodile, Fish Scleropages formosus or Asian arawana.

• Siberut, 00°55' to 03°20'S; 98°31' to 100°40'E, 4.050 km2. It is the largest of the Mentawai Islands, west of Sumatra, with 65% of endemic species. Subtropical wet forest and coral reefs.

Indonesian ethnic groups

Badui people members at an event in 2017

There are 1,340 recognized ethnic groups in Indonesia. The vast majority of them belong to the Austronesian peoples.

According to ethnic classification, the largest ethnic group in Indonesia is the Javanese, who make up about 40% of the total population. The Javanese are concentrated on the island of Java, particularly in the central and eastern parts. The Sundanese are the next largest group; their homeland is located in the western part of the island of Java and the southern tip of Sumatra. The Sunda Strait is named after him. Malays, Batak, Madurese, Batavi, Minangkabau and Bugis are the next largest groups in the country.

Many ethnic groups, particularly in Kalimantan and Papua, have only hundreds of members. Most of the local languages belong to the Austronesian language family, although a significant number of people, particularly in eastern Indonesia, speak unrelated Papuan languages. Chinese Indonesians make up just under 1% of the total Indonesian population according to the 2000 census. Some of these Chinese-ancestry Indonesians speak several Chinese languages, most notably Southern Min and Hakka.

The classification of ethnic groups in Indonesia is not rigid and in some cases unclear due to migrations, cultural and linguistic influences; for example, the Bantenese may be considered by some to be members of the Sundanese people; however, others argue that they are completely different ethnic groups as they have their own distinct dialects. This is also the case for the Badui people, who share many cultural similarities with the Sundanese people. An example of a hybrid ethnicity is the Batavi people, descendants not only of marriages between different native Indonesian peoples, but also of intermarriage with Arab, Chinese and Indian immigrants since the colonial era of Batavia (present-day Jakarta).

Ethnic groups in Indonesia