Lake Toba

Coordinates: 2°41′N 98°53′E / 2.68°N 98.88°E / 2.68; 98.88
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Lake Toba
Danau Toba (Indonesian)
A view of Lake Toba and Samosir Island
Lake Toba is located in Indonesia
Lake Toba
Lake Toba
Lake Toba is located in Sumatra
Lake Toba
Lake Toba
LocationBalige, North Sumatra
Coordinates2°41′N 98°53′E / 2.68°N 98.88°E / 2.68; 98.88
TypeVolcanic/tectonic
Part ofAsahan Toba basin
Primary outflowsAsahan River
Basin countries Indonesia
Max. length100 km (62 mi)
Max. width30 km (19 mi)
Surface area1,130 km2 (440 sq mi)
Average depth216 m (709 ft)
Max. depth505 m (1,657 ft)[1]
Water volume244 km3 (59 cu mi)
Surface elevation905 m (2,969 ft)
IslandsSamosir
SettlementsAmbarita, Pangururan
References[1]

Lake Toba (

UNESCO Global Geoparks.[3][4][5]

Lake Toba is the site of a

VEI 8 that occurred 69,000 to 77,000 years ago,[6][7][8] representing a climate-changing event. Recent advances in dating methods suggest a more accurate identification of 74,000 years ago as the date.[9] It is the largest-known explosive eruption on Earth in the last 25 million years. According to the Toba catastrophe theory, the eruption had global consequences for human populations as it killed most humans living at that time and is believed to have created a population bottleneck in central east Africa and India, which affects the genetic make-up of the human worldwide population to the present.[10] More recent studies had cast doubt on this theory and found no evidence of substantial changes in global population.[11]

It was also suggested that the eruption of the Toba Caldera led to a volcanic winter with a worldwide decrease in temperature between 3 and 5 °C (5.4 and 9.0 °F), and up to 15 °C (27 °F) in higher latitudes. Additional studies in Lake Malawi in East Africa show significant amounts of ash being deposited from the Toba Caldera eruptions, even at that great distance, but little indication of a significant climatic effect in East Africa.[12]

Geology

Batu Gantung (Hanging stone) in Lake Toba
Map of the lake

The Toba Caldera in North Sumatra comprises four overlapping volcanic craters that adjoin the Sumatran "volcanic front". At 100 by 30 kilometres (62 by 19 mi) it is the world's largest Quaternary caldera, and the fourth and youngest caldera. It intersects the three older calderas. An estimated 2,800 km3 (670 cu mi) of dense-rock equivalent pyroclastic material, known as the youngest Toba tuff, was released during one of the largest explosive volcanic eruptions in recent geological history.[13] Following this eruption, a resurgent dome formed within the new caldera, joining two half-domes separated by a longitudinal graben.[7]

At least four cones, four

solfatarically active.[14]

Major eruption

Main article: Toba catastrophe theory
Location of Lake Toba shown in red on map

The Toba eruption (the Toba event) occurred at what is now Lake Toba about 73,700±300 years ago.

volcanic eruption
in the Quaternary.

Bill Rose and Craig Chesner of Michigan Technological University have estimated that the total amount of material released in the eruption was at least 2,800 km3 (670 cu mi)[17]—about 2,000 km3 (480 cu mi) of ignimbrite that flowed over the ground, and approximately 800 km3 (190 cu mi) that fell as ash mostly to the west. However, as more outcrops become available, Toba possibly erupted 3,200 km3 (770 cu mi) of ignimbrite and co-ignimbrite. The pyroclastic flows of the eruption destroyed an area of least 20,000 km2 (7,700 sq mi), with ash deposits as thick as 600 m (2,000 ft) by the main vent.[17] The eruption was large enough to have deposited an ash layer approximately 15 cm (6 in) thick over all of South Asia; at one site in central India, the Toba ash layer today is up to 6 m (20 ft) thick[18] and parts of Malaysia were covered with 9 m (30 ft) of ash fall.[19]

The subsequent collapse formed a caldera that filled with water, creating Lake Toba. The island in the center of the lake is formed by a resurgent dome.

Landsat
photo of Sumatra surrounding Lake Toba

The exact year of the eruption is unknown, but the pattern of ash deposits suggests that it occurred during the northern summer because only the

Ice cores from Greenland record a pulse of starkly reduced levels of organic carbon sequestration. Very few plants or animals in southeast Asia would have survived, and it is possible that the eruption caused a planet-wide die-off. However, the global cooling has been discussed by Rampino and Self. Their conclusion is that the cooling had already started before Toba's eruption. This conclusion was supported by Lane and Zielinski who studied the lake-core from Africa and GISP2. They concluded that there was no volcanic winter after the Toba eruption and that high H2SO4 deposits do not cause long-term effects.[21][22] Furthermore, due to the low solubility of sulfur in the magma, the emission of volatiles and climate impacts are likely limited.[23]

Evidence from studies of

University of Illinois at Urbana–Champaign in 1998, the effects of the Toba eruption may have decreased the size of human populations to only a few tens of thousands of individuals.[24] However, this hypothesis is not widely accepted because similar effects on other animal species have not been observed, and paleoanthropology suggests there was no population bottleneck.[25][26] The genetic bottleneck is now recognized to be the Out-of-Africa founder effect, rather than an actual reduction in population.[27]

More recent activity

Since the major eruption ~70,000 years ago, eruptions of smaller magnitude have also occurred at Toba. The small cone of Pusukbukit formed on the southwestern margin of the caldera and lava domes. The most recent eruption may have been at Tandukbenua on the northwestern caldera edge, suggested by a lack of vegetation that could be due to an eruption within the last few hundred years.[28]

Some parts of the caldera have shown uplift due to partial refilling of the magma chamber, for example, pushing Samosir Island and the Uluan Peninsula above the surface of the lake. The lake sediments on Samosir Island show that it has risen by at least 450 m (1,476 ft)[16] since the cataclysmic eruption. Such uplifts are common in very large calderas, apparently due to the upward pressure of below-ground magma. Toba is probably the largest resurgent caldera on Earth. Large earthquakes have recently occurred in the vicinity of the volcano, notably in 1987 along the southern shore of the lake at a depth of 11 km (6.8 mi).[29] Such earthquakes have also been recorded in 1892, 1916, and 1920–1922.[16]

In 2016, a study revealed that the Toba Supervolcano has a magma chamber containing 50,000 cubic kilometres (12,000 cu mi) of eruptible magma, about 30–50 kilometres (19–31 mi) underground.[30] This makes the supervolcano's magma chamber more than four times larger than the volume of Lake Superior in North America, and also larger than the magma chamber underneath Yellowstone.[31]

Lake Toba lies near the

subduction zone in this area is very active: the seabed near the west coast of Sumatra has had several major earthquakes since 1995, including the 9.1 2004 Indian Ocean earthquake and the 8.7 2005 Nias–Simeulue earthquake
, the epicenters of which were around 300 km (190 mi) from Toba.

People

Batak canoes near Haranggaol on Lake Toba (circa 1920)

Most of the people who live around Lake Toba are ethnically

Bataks. Traditional Batak houses are noted for their distinctive roofs (which curve upwards at each end, as a boat's hull does) and their colorful decor.[32]

Transportation

Pematang Siantar by a 48 km road. Sisingamangaraja XII International Airport
is located about 47 mi (76 km) from Parapat.

Flora and fauna

The

macrophytes, floating macrophytes, and submerged macrophytes, while the surrounding countryside is rainforest including areas of Sumatran tropical pine forests on the higher mountainsides.[33]

The

Xiphophorus hellerii.[36]

Panoramic view of Lake Toba

Sinking of MV Sinar Bangun

Main article: Sinking of MV Sinar Bangun

On 18 June 2018, Lake Toba was the scene of a ferry disaster, in which over 160 people drowned.[37] MV Sinar Bangun was an irregular operating vessel on the lake which capsized with many passengers on board. The incident caused the death of 167 people and injuries to a number of others. Preliminary reports found the vessel was in operation with irregularities. Ignoring overloading on the vessel and operating in rough weather conditions were concluded to be the main reasons leading to the disaster.

In popular culture

The Origin of Lake Toba is a folk story about the lake, in which once upon a time, there was a fisherman who caught a golden fish. Samosir Island is believed to be the golden fish's son.[38]

Gallery

  • Lake Toba Aerial View
    Lake Toba Aerial View
  • Aerial view of the southern shore with Sibandang Island visible in the background
    Aerial view of the southern shore with Sibandang Island visible in the background
  • View of the lake with an example of Batak architecture in the foreground
    View of the lake with an example of Batak architecture in the foreground
  • Traditional Batak house at Ambarita, Lake Toba
    Traditional Batak house at Ambarita, Lake Toba
  • Sipiso-Piso Waterfall
    Sipiso-Piso Waterfall
  • Lake Toba from Tongging Village, near Sipiso-Piso Waterfall
    Lake Toba from Tongging Village, near Sipiso-Piso Waterfall
  • Lake Toba featured in 1,000-rupiah banknote
    Lake Toba featured in 1,000-rupiah banknote
  • Details of carvings on the prow of a Toba Batak canoe
    Details of carvings on the prow of a Toba Batak canoe
  • The caldera of Lake Toba, with a resurgent dome, forming Samosir Island
    The caldera of Lake Toba, with a resurgent dome, forming Samosir Island
  • A panoramic partial view of Toba Lake, as seen from the west side to the southeast
    A panoramic partial view of Toba Lake, as seen from the west side to the southeast

See also

References

  1. ^ a b c "LakeNet – Lakes".
  2. ^ "Gov't Expects UNESCO to Recognize Kaldera Toba Geopark This Year". Tempo. Retrieved 16 July 2018.
  3. ^ Gunawan, Apriadi (8 July 2020). "Toba caldera finally recognized as UNESCO Global Geopark". The Jakarta Post. Retrieved 9 July 2020.
  4. ^ "Lake Toba proposed as world geopark heritage site". The Jakarta Post. Retrieved 16 July 2018.
  5. ^ "Perjalanan Geopark Kaldera Danau Toba Masuk Daftar UGG". Kompas. Retrieved 16 July 2018.
  6. ^ "Toba: General Information". Global Volcanism Program. Smithsonian Institution. Retrieved 24 June 2021.
  7. ^
    doi:10.1130/0091-7613(1991)019<0200:EHOESL>2.3.CO;2
    . Retrieved 23 August 2008.
  8. S2CID 4364788
    .
  9. ^ Vogel, Gretchen, How ancient humans survived global ‘volcanic winter’ from massive eruption, Science, 12 March 2018
  10. ^ "When humans faced extinction". BBC. 9 June 2003. Retrieved 5 January 2007.
  11. PMID 29477183
    . Retrieved 1 August 2020.
  12. PMID 23630269
    .
  13. PMID 28120860
    .
  14. ^ "Toba: Synonyms & Subfeatures". Global Volcanism Program. Smithsonian Institution. Retrieved 24 June 2021.
  15. ISSN 1871-1014
    .
  16. ^ a b c d Stratigraphy of the Toba Tuffs and the evolution of the Toba Caldera Complex, Sumatra, Indonesia
  17. ^
    USGS
    . 28 April 2005.
  18. S2CID 128545662
    .
  19. OCLC 3575130
    ., noted by Weber.
  20. doi:10.1130/0091-7613(2000)028<0275:TALITS>2.3.CO;2.{{cite journal}}: CS1 maint: numeric names: authors list (link
    )
  21. PMID 23630269
    .
  22. doi:10.1029/96GL00706
    .
  23. ISSN 0377-0273
    .
  24. ^ "Yellowstone Is a Supervolcano?". Biot Reports (164). Suburban Emergency Management Project. 11 January 2005. Archived from the original on 13 January 2008. Retrieved 21 February 2008.
  25. ^ Gathorne-Hardy, F. J., and Harcourt-Smith, W. E. H., "The super-eruption of Toba, did it cause a human bottleneck?" Archived 14 October 2013 at the Wayback Machine, Journal of Human Evolution 45 (2003) 227–230.
  26. doi:10.1016/j.quaint.2011.07.042
    .
  27. PMID 21753753
    .
  28. ^ "Toba volcano (Indonesia, Sumatra)". VolcanoDiscovery.com.
  29. ^ "Significant Earthquakes of the World". United States Geological Survey (USGS).
  30. PMID 27433784
    .
  31. ^ Robin Andrews (20 July 2016). "The Toba Supervolcano Has A Bigger Underground Magma Chamber Than Yellowstone". iflscience.com. IFL Science!. Retrieved 2 April 2021.
  32. ^ "Batak People". IndonesianMusic.com. Archived from the original on 13 August 2008.
  33. ^ "Danau Toba (Lake Toba)". International Lake Environment Committee. Archived from the original on 3 March 2009.
  34. S2CID 86114358
    .
  35. ^
    doi:10.1046/j.1440-1770.2001.00155.x
    .
  36. ^ a b FishBase (2012). Species in Toba. Accessed 25 January 2012
  37. ^ "Indonesia ferry disaster: Lake Toba captain detained". BBC. 21 June 2018. Retrieved 25 June 2018.
  38. ISSN 2477-3328. {{cite journal}}: Cite journal requires |journal= (help
    )

Further reading

External links

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