Toba catastrophe

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Satellite image of Lake Toba: 100km long and 30km wide. The lake is the caldera of a supervolcano
Position of Lake Toba

Toba [1] is a lake in the caldera of a supervolcano. The lake is 100 kilometres long and 30 kilometres wide, and 505 metres (1,666 ft) at its deepest point.

It is in the middle of the northern part of the Indonesian island of Sumatra with an elevation of about 900 metres (2,953 ft). The lake stretches from 2°53′N 98°31′E / 2.88°N 98.52°E / 2.88; 98.52 to 2°21′N 99°06′E / 2.35°N 99.1°E / 2.35; 99.1. It is the largest lake in Indonesia and the largest volcanic lake in the world.[2]

Huge eruption[change | edit source]

Lake Toba is the site of a supervolcanic eruption that occurred 73,000 (±4000 years) years ago.[3][4][5] This was the largest eruption in the last two million years,[4] and the largest known eruption in the Phanerozoic era.[6] It was a climate-changing event. The eruption was two orders of magnitude (= x100) larger than the largest known historic eruption, that of Tambora, also in Indonesia.[4]

Consequences[change | edit source]

The eruption of Toba led to a volcanic winter with a worldwide decline in temperatures between 3-5 degrees C, and up to 15 degrees C in higher latitudes.[7]

Effect on humans[change | edit source]

According to the Toba catastrophe theory it had global consequences, killing most humans then alive and creating a population bottleneck in Central Eastern Africa and India that affected the genetic inheritance of all humans today.[7][8]

According to the theory, only 10,000 (perhaps only 1,000) pairs of humans survived the disaster. Perhaps it led to the other hominids becoming extinct, though the Neanderthals certainly survived in Europe and Eurasia.

There is no direct evidence that the theory is correct. And there is no evidence for any other animal decline or extinction, even in environmentally sensitive species.[9] There is evidence that human habitation continued in India after the eruption.[10] The theory in its strongest form seems to be incorrect.

References[change | edit source]

  1. Indonesian: Danau Toba
  3. Global Volcanism Program page on Toba
  4. 4.0 4.1 4.2 Chesner C.A. et al. (1991). "Eruptive history of Earth's largest Quaternary caldera (Toba, Indonesia)". Michigan Technological University. Retrieved 2008-08-23.
  5. Ninkovich, D.; N.J. Shackleton et al (1978). "K−Ar age of the late Pleistocene eruption of Toba, north Sumatra". Nature 276: 574–577. doi:10.1038/276574a0.
  6. Ambrose S.H. Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern human populations. J. Human Evolution. 34, 623–651.
  7. 7.0 7.1 "When humans faced extinction". BBC. 2003-06-09. Retrieved 2007-01-05.
  8. Robock A. et al. (2009). "Did the Toba volcanic eruption of ~74k BP produce widespread glaciation?". Journal of Geophysical Research 114: D10107. doi:10.1029/2008JD011652.
  9. Gathorne-Hardy F.J. & Harcourt-Smith W.E.H. 2003. The super-eruption of Toba: did it cause a human bottleneck? Journal of Human Evolution. 45, 227-230
  10. Petraglia M et al. 2007. "Middle Paleolithic assemblages from the Indian subcontinent before and after the Toba super-eruption". Science 317 (5834): 114–116. doi:10.1126/science.1141564. PMID 17615356.