Editing Sumatra (section)

== Geography ==
[[File:Sumatra Volcanoes.png|thumb|Map of geological formation of Sumatra island]]
[[File:Sinabung.jpg|thumb|[[Mount Sinabung]], North Sumatra]]

The longest axis of the island runs approximately {{convert|1790|km|abbr=on}} northwest–southeast, crossing the equator near the centre. At its widest point, the island spans {{convert|435|km|mi|abbr=on}}. The interior of the island is dominated by two geographical regions: the [[Barisan Mountains]] in the west and swampy plains in the east. Sumatra is the closest Indonesian island to mainland Asia.

To the southeast is [[Java]], separated by the [[Sunda Strait]]. To the north is the [[Malay Peninsula]] (located on the Asian mainland), separated by the [[Strait of Malacca]]. To the east is [[Borneo]], across the [[Karimata Strait]]. West of the island is the [[Indian Ocean]].

Sumatra is a highly seismic island. The [[Great Sumatran fault]] (a [[Fault (geology)#Strike-slip faults|strike-slip]] fault), and the [[Sunda megathrust]] (a [[subduction zone]]), run the entire length of the island along its west coast. Huge earthquakes have been recorded throughout history. In 1797, an 8.9 earthquake shook Western Sumatra, and in 1833, a 9.2 earthquake shook Bengkulu and Western Sumatra. Both events caused large [[tsunami]]s. Earthquakes are very common throughout the coastal area of the west and center of the island, and tsunamis are common due to the high seismicity in the area.<ref>{{Cite journal |date=December 2020 |title=Coastal and settlement typologies-based tsunami modeling along the northern Sumatra seismic gap zone for disaster risk reduction action plans |url=https://www.sciencedirect.com/science/article/abs/pii/S2212420920313029#:~:text=The%20main%20potential%20source%20of,zone%20%5B2%2C13%5D. |journal=International Journal of Disaster Risk Reduction |volume=51|bibcode=2020IJDRR..5101800J |last1=Jihad |first1=Abdi |last2=Muksin |first2=Umar |author3=Syamsidik |last4=Suppasri |first4=Anawat |last5=Ramli |first5=Marwan |last6=Banyunegoro |first6=Vrieslend H. |doi=10.1016/j.ijdrr.2020.101800 |url-access=subscription }}</ref><ref>{{Cite web |title=Earthquakes and Tsunamis in Sumatra |url=http://www.tectonics.caltech.edu/outreach/highlights/sumatra/ |access-date=2024-04-06 |website=www.tectonics.caltech.edu}}</ref>

On 26 December 2004, the western coast and islands of Sumatra, particularly [[Aceh]] province, were struck by a [[tsunami]] following the [[2004 Indian Ocean earthquake|Indian Ocean earthquake]]. This was the longest earthquake recorded, lasting between 500 and 600 seconds (8.33–10 minutes).<ref>{{Cite book| title=Guinness Book of World Records 2014| chapter= Dynamic Earth| last=Glenday| first=Craig| publisher=The Jim Pattison Group| year=2013| isbn=978-1-908843-15-9| page=[https://archive.org/details/guinnessworldrec0000unse_r3e7/page/015 15]| chapter-url=https://archive.org/details/guinnessworldrec0000unse_r3e7/page/015| quote= 26 December 2004: Longest earthquake...between 500 and 600 seconds.}}</ref> More than 170,000 Indonesians were killed, primarily in Aceh. Other recent earthquakes to strike Sumatra include the [[2005 Nias–Simeulue earthquake]] and the [[2010 Mentawai earthquake and tsunami]].

[[Lake Toba]] is the site of a [[Supervolcano|supervolcanic]] [[types of volcanic eruptions|eruption]] that occurred around 74,000 years ago, representing a climate-changing event.<ref>{{cite web| last= Vogel| first= Gretchen| url= https://www.science.org/content/article/how-ancient-humans-survived-global-volcanic-winter-massive-eruption?et_rid=382659176&et_cid=1903121| title= How ancient humans survived global 'volcanic winter' from massive eruption| work= [[Science (journal)|Science]]| date= 12 March 2018| access-date= October 11, 2023| archive-date= 9 August 2022| archive-url= https://web.archive.org/web/20220809093043/https://www.science.org/content/article/how-ancient-humans-survived-global-volcanic-winter-massive-eruption?et_rid=382659176&et_cid=1903121| url-status= live}}</ref> The most important rivers in Sumatra belong to the catchment area of the [[South China Sea]]. Heading north to south, the [[Asahan River|Asahan]], [[Rokan River|Rokan]], [[Siak River|Siak]], [[Kampar River|Kampar]], [[Indragiri River|Indragiri]], [[Batang Hari River|Batanghari]] flow into the [[Strait of Malacca|Malacca Strait]], while the island's largest river, the [[Musi River (Indonesia)|Musi]], flows into the sea at [[Bangka Strait]] in the south. To the east, big rivers carry silt from the mountains, forming the vast lowland interspersed by swamps. Even if mostly unsuitable for farming, the area is currently of great economic importance for Indonesia. It produces oil from both above and below the soil – [[Oil palm|palm oil]] and [[petroleum]].

Sumatra is the largest producer of [[Indonesian coffee]]. Small-holders grow Arabica coffee (''[[Coffea arabica]]'') in the highlands, while Robusta (''[[Coffea canephora]]'') is found in the lowlands. Arabica coffee from the regions of Gayo, Lintong and Sidikilang is typically processed using the [[Giling Basah]] (wet hulling) technique, which gives it a heavy body and low acidity.<ref>{{Cite web |title=Daerah Produsen Kopi Arabika di Indonesia |url=http://kopidistributor.com/sekilas-info/daerah-produsen-kopi-arabika-di-indonesia |date=28 February 2015 |website= KopiDistributor.com |trans-title=Regional Arabica Coffee Producers in Indonesia | language= Indonesian| publisher= KD 1995 |url-status=live |archive-url=https://web.archive.org/web/20150402094956/http://kopidistributor.com/sekilas-info/daerah-produsen-kopi-arabika-di-indonesia |archive-date=2 April 2015 |access-date=28 February 2015}}</ref>

[[File:Medan_skyline_(2022).jpg|thumb|upright=1.35|[[Medan]], the largest city in Sumatra]]
By population, Medan is the largest city in Sumatra.<ref name="Biro Pusat Statistik, Jakarta">Biro Pusat Statistik, Jakarta.</ref> Medan is also the most visited and developed city in Sumatra.