Editing Geography of Indonesia (section)

==Geology==
{{main|Geology of Indonesia}}
[[File:Plate setting Sunda megathrust.png|thumb|left|330x330px|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 {{convert|300|m|0}} 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 {{convert|4500|m|0}} 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 that 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 Islands|Sangihe]] and [[Talaud Islands]], southwest of the [[Philippine Trench]].<ref>{{Cite book|url=https://books.google.com/books?id=eilFDwAAQBAJ&q=Mindanao+North+Sulawesi+Arc&pg=PT190|title=Mountains: The origins of the Earth's mountain systems|last=Park|first=Graham|date=2018-01-03|publisher=Dunedin Academic Press|isbn=9781780465791|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=S68JAQAAIAAJ&q=North+Sulawesi+tectonics|title=The Geology and Tectonics of Eastern Indonesia: Proceedings of the Ccop-Ioc Seatar Working Group Meeting, Bandung, Indonesia, 9–14 July 1979|last=Wiryosujono|first=S.|date=1981|publisher=Pergamon Press|isbn=9780080287324|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=FyQUAQAAIAAJ&q=Sangihe+Talaud+Philippine+Trench|title=Tectonic Evolution of Southeast Asia|last1=Hall|first1=Robert|last2=Blundell|first2=Derek John|date=1996|publisher=Geological Society|isbn=9781897799529|language=en}}</ref>

Nusa Tenggara 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.<ref>{{WWF ecoregion|id=aa0102|name=Banda Sea Islands moist deciduous forests}}. Worldwildlife.org. Retrieved on 29 September 2010.</ref> 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.
[[File:Erupsi Gunung Sinabung 9 Juni 2019 oleh Muh Ma'rufin Sudibyo.jpg|thumb|upright|2019 eruption of [[Mount Sinabung|Sinabung]] in [[North Sumatra]]. Sinabung is one of the most active volcanoes in Indonesia.]]
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.<ref>{{WWF ecoregion|id=aa0104|name=Terrestrial Ecoregions - Buru rain forests (AA0104)}}. Worldwildlife.org. Retrieved on 29 September 2010.</ref> 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]].<ref>Carter, D. J., Audley-Charles, M. G. & Barber, A. J. Stratigraphical analysis of island arc-continental margin collision in eastern Indonesia. J. Geol. Soc. Lond. 132, 179-189 (1976).</ref><ref>Hamilton, W. Tectonics of the Indonesian Region Vol. 1078 (US Geol. Soc. Prof. Pap., 1979).</ref> The sea also contains the Weber Deep, one of the deepest point in Indonesia.<ref>{{Cite book|url=https://books.google.com/books?id=62zMI9P4Vv8C&q=%22Weber+Deep%22+Banda+Sea+deepest&pg=PA272|title=Ecosystems of the Deep Oceans|last=Tyler|first=P. A.|date=2003-03-27|publisher=Elsevier|isbn=9780080494654|language=en}}</ref><ref>{{Cite news|url=http://www.thejakartapost.com/life/2016/11/29/biggest-exposed-fault-on-earth-found-in-eastern-indonesia.html|title=Biggest exposed fault on earth found in eastern Indonesia|date=29 November 2016|work=The Jakarta Post|access-date=2018-02-17|language=en}}</ref>

[[Geomorphology|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]].<ref name="aims">{{cite web|url=http://www.aims.gov.au/pages/reflib/bigbank/pages/bb-04.html|title=Big Bank Shoals of the Timor Sea: An environmental resource atlas|year=2001|publisher=Australian Institute of Marine Science|archive-url=https://web.archive.org/web/20060908082408/http://www.aims.gov.au/pages/reflib/bigbank/pages/bb-04.html|archive-date=8 September 2006|url-status=dead|access-date=2006-08-28}}</ref><ref name="wirantaprawira">{{cite web|url=http://www.wirantaprawira.net/indon/land.html|title=Republik Indonesia|last=Wirantaprawira|first=Dr Willy|year=2003|publisher=Dr Willy Wirantaprawira|archive-url=https://web.archive.org/web/20061018140046/http://www.wirantaprawira.net/indon/land.html|archive-date=2006-10-18|url-status=live|access-date=2006-08-28}}</ref> 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.<ref name="JohnsonPage12">{{cite book|title=The Geology of Australia|last=Johnson|first=David Peter|publisher=[[Cambridge University Press]]|year=2004|location=Port Melbourne, Victoria|page=12}}</ref> The [[New Guinea Highlands]] range some {{convert|650|km|0}} 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.<ref>MG Audley-Charles, 1986, "Timor–Tanimbar Trough: the foreland basin of the evolving Banda orogen", ''Spec. Publs int. Ass. Sediment'', 8:91–102</ref><ref>{{Cite book|url=https://books.google.com/books?id=Ch_1JlLkKE0C&q=new+guinea+north+west+tectonics&pg=PA4|title=Evolution and Dynamics of the Australian plate|last1=Hillis|first1=R. R.|last2=Müller|first2=R. D.|date=2003-01-01|publisher=Geological Society of America|isbn=9780813723723|language=en}}</ref>

===Tectonism and volcanism===
{{main|Volcanoes of Indonesia}}
Most of the larger islands are mountainous, with peaks ranging between {{convert|2000|and|3800|m|0}} meters above sea level in Sumatra, Java, Bali, Lombok, Sulawesi, and Seram.<ref>{{Cite book|url=https://books.google.com/books?id=GwRWAAAAYAAJ&q=Indonesia+landform+mountain+range|title=Focus on Indonesia|date=1976|publisher=Information Division, Embassy of Indonesia|language=en}}</ref> The country's tallest mountains are located in the [[Jayawijaya Mountains]] and the [[Sudirman Range]] in Papua. The highest peak, [[Puncak Jaya]] ({{convert|4884|m|0}}), is located in the Sudirman Mountains. A string of volcanoes stretches from Sumatra to Nusa Tenggara,<ref>{{cite book|title=Indonesia|last=Witton|first=Patrick|publisher=Lonely Planet|year=2003|isbn=1-74059-154-2|location=Melbourne|page=38}}</ref> then loops around through to the [[Banda Islands]] of Maluku to northeastern Sulawesi. Of the 400 volcanoes, approximately 150 are active.<ref name="gvp">{{cite web|url=http://www.volcano.si.edu/world/region.cfm?rnum=06&rpage=list|title=Volcanoes of Indonesia|work=[[Global Volcanism Program]]|publisher=[[Smithsonian Institution]]|access-date=25 March 2007}}</ref> 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.

[[Image:Map indonesia volcanoes.gif|thumb|446x446px|A map of [[List of volcanoes in Indonesia|Indonesia's volcanoes]].]]
Indonesia has relatively high tectonic and volcanic activities. It lies on the convergence between the [[Eurasian plate|Eurasian]], [[Indo-Australian plate|Indo-Australian]], [[Pacific plate|Pacific]], and [[Philippine Sea plate]]. The [[Sunda megathrust]] is a 5,500&nbsp;km long fault located off southern coasts of Sumatra, Java and Lesser Sunda Islands, where the Indo-Australian Plate is thrusting northeastward towards the subducting Sunda Plate. Tectonic movement in this fault is responsible for the creation of the [[Sunda Trench]], and mountain ranges across Sumatra, Java, and the Lesser Sunda Islands.<ref>{{Cite book|url=https://books.google.com/books?id=WOmRkO9fsiwC&q=Sunda+megathrust+trench+mountain&pg=PA2|title=From the Ground Up: Perspectives on Post-Tsunami and Post-Conflict Aceh|last1=Daly|first1=Patrick|last2=Feener|first2=R. Michael|last3=Reid|first3=Anthony J. S.|date=2012|publisher=Institute of Southeast Asian Studies|isbn=9789814345194|language=en}}</ref> Many great earthquakes occurred in the vicinity of the fault, such as the [[2004 Indian Ocean earthquake and tsunami|2004 Indian Ocean earthquake]].<ref>{{Cite book|url=https://books.google.com/books?id=1bY6DwAAQBAJ&q=%22Sunda+megathrust%22&pg=PA69|title=Geohazards in Indonesia: Earth Science for Disaster Risk Reduction|last1=Cummins|first1=P. R.|last2=Meilano|first2=I.|date=2017-10-25|publisher=Geological Society of London|isbn=9781862399662|language=en}}</ref> [[Mount Merapi]], located in the Java portion of the megathrust, is the most active [[volcano]] in Indonesia and is designated as one of world's [[Decade Volcanoes]] due to the hazard it poses to the surrounding populated areas.<ref>{{Cite book|url=https://books.google.com/books?id=1j0AaQXWORkC&q=Merapi+decade+volcanoes&pg=PA1418|title=Geodetic And Geophysical Effects Associated With Seismic And Volcanic Hazards|last=Fernandez|first=José|date=2004-06-25|publisher=Springer Science & Business Media|isbn=9783764370442|language=en}}</ref> The 2004 Indian Ocean earthquake and tsunami devastated the Indonesian provinces of Aceh and North Sumatra, resulting in approximately 225,000 deaths and leaving over 425,000 people homeless. The disaster caused significant damage to infrastructure, homes, and local industries. The Indonesian government, in partnership with international organizations like the IMF, World Bank, and ADB, coordinated relief and reconstruction efforts. Preliminary assessments estimated the reconstruction cost at $4-5 billion over five years. During a donor meeting in January 2005, nearly $4 billion in aid was pledged for reconstruction, with a focus on transparency and efficient fund management. Despite the severe local impact, the overall effect on Indonesia’s national GDP was limited, as the Aceh region contributed only about 2% of national output. The Paris Club also offered a temporary debt moratorium, which helped fund rebuilding without diverting domestic financial resources.<ref>{{Cite web |title=Preliminary Assessment of the Macroeconomic Impact of The Tsunami Disaster on Affected Countries, and of Associated Financing Needs |url=https://www.imf.org/external/np/oth/2005/020405.htm |access-date=2024-11-16 |website=www.imf.org}}</ref>

The northern part of Sulawesi and Maluku Islands lie on the convergence of Sunda Plate and [[Molucca Sea plate]], making it an active tectonic region with volcanic chains such as the [[Sangihe Islands|Sangihe]] and [[Talaud Islands]].<ref>{{Cite book|url=https://books.google.com/books?id=9YFGGjz1oVsC&q=Sunda+Molucca+Sea+Plate&pg=PA29|title=Dynamics of Crustal Magma Transfer, Storage and Differentiation|last1=Annen|first1=Catherine|last2=Zellmer|first2=Georg F.|date=2008|publisher=Geological Society of London|isbn=9781862392588|language=en}}</ref> Northern Maluku and western New Guinea is located on the convergence of [[Bird's Head plate|Bird's Head]], [[Philippine Sea plate|Philippine Sea]] and [[Caroline plate]]. It is also a seismically active region, with the 7.6 [[Moment magnitude scale|M<sub>w</sub>]] [[2009 Papua earthquakes]] being the most recent great earthquake to date in the region.<ref>{{Cite book|url=https://books.google.com/books?id=FyQUAQAAIAAJ&q=Philippine+Caroline+Bird's+Head+Plate|title=Tectonic Evolution of Southeast Asia|last1=Hall|first1=Robert|last2=Blundell|first2=Derek John|date=1996|publisher=Geological Society|isbn=9781897799529|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=1bY6DwAAQBAJ&q=2009+Manokwari+earthquake&pg=PA103|title=Geohazards in Indonesia: Earth Science for Disaster Risk Reduction|last1=Cummins|first1=P. R.|last2=Meilano|first2=I.|date=2017-10-25|publisher=Geological Society of London|isbn=9781862399662|language=en}}</ref><ref>{{Cite web|url=https://earthquaketrack.com/quakes/2009-01-03-22-33-40-utc-7-4-23|title=7.4 magnitude earthquake near Manokwari, West Papua, Indonesia : January 03, 2009 22:33|website=earthquaketrack.com|language=en|access-date=2018-02-06}}</ref>