Super-eruptions and their impacts on climate, environment and human populations
Around 74,000 years ago, Toba volcano in northern Sumatra erupted, disgorging around 2800 km3 of magma, and blanketing ash across an area stretching between the Arabian Sea in the west, the central Indian Ocean basin in the south, and the South China Sea in the east. The eruption is the largest known on Earth in the last 2 million years. It is the most recent example of a volcanic 'super-eruption', a class of eruption that happens on average once every 700,000 years. The scale and impact of even the most devastating volcanic eruptions in history, such as Tambora and Krakatau, are likely to pale in comparison with those resulting from eruptions the size of Toba.
Figure 1. Distribution of recovered ash-fall deposits from the Toba eruption of 74,000 years ago (circles). A team of archaeologists and volcanologists from Cambridge has been working at Jwalapuram (star), where Toba ash has been found in abundance.
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Members of the Cambridge Volcanology Group, including Clive Oppenheimer, have been working with a team of archaeologists led by Michael Petraglia (Leverhulme Centre for Human Evolutionary Studies) and Ravi Korisettar who recently discovered rich Toba ash localities in India in association with a variety of stone tool assemblages. Aims of the project include investigation of the potential environmental impacts of ash fall and climate change in India, and the consequences for the human population. This research, which includes detailed analyses of the ash deposits themselves, is complemented by atmospheric and climate modelling involving Hans Graf in the Department of Geography. New work is being supported by a grant from the Leverhulme Trust ("The Toba super-eruption and its impact on human populations and ecosystems").
Figure 2. Light -toned Toba tephra in excavation at Jwalapuram, India.
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References:
- Petraglia, M.P., Korisettar, R., Boivin, N., Clarkson, C., Ditchfield, P., Jones, S., Koshy, J., Lahr, M., Oppenheimer, C., Pyle, D., Roberts, R., Schwenninger, J.L., Arnold, L., and White, K., 2007, Middle paleolithic assemblages from the Indian subcontinent before and after the Toba super-eruption, Science, 317, 114-116.
- Witham, C.S. and Oppenheimer, C., 2005, Mortality in England during the 1783-4 Laki Craters eruption, Bulletin of Volcanology, 67, 15-26.
- Mason, B.G., Pyle, D.M. and Oppenheimer, C., 2004, The size and frequency of the largest explosive eruptions on Earth, Bulletin of Volcanology, 66, 735-748.
- Oppenheimer, C., 2003, Climatic, environmental and human consequences of the largest known historic eruption: Tambora volcano (Indonesia) 1815, Progress in Physical Geography, 27, 230-259.
- Oppenheimer, C., 2003, Ice core and palaeoclimatic evidence for the great volcanic eruption of 1257, International Journal of Climatology, 23, 417-426.
- Oppenheimer, C., 2002, Limited global change due to largest known Quaternary eruption, Toba ≈74 kyr BP?, Quaternary Science Reviews, 21, 1593-1609.
Figure 3. Sampling and logging pit walls at Jwalapuram
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