The Toba supereruption (Youngest Toba Tuff) was a supervolcanic eruption that occurred some time between 69,000 and 77,000 years ago at Lake Toba (Sumatra, Indonesia). It is recognized as one of the Earth’s largest known eruptions. The related catastrophe theory holds that this event plunged the planet into a 6-to-10-year volcanic winter and possibly an additional 1,000-year cooling episode. This change in temperature is allege to have resulted in the world’s human population being reduced to 10,000 or even a mere 1,000 breeding pairs, creating a bottleneck in human evolution.
Although the Toba eruption took place in Indonesia, it deposited an ash layer approximately 15 centimetres thick over the entirety of South Asia. A blanket of volcanic ash was also deposited over the Indian Ocean, and the Arabian and South China Sea.