The erupted mass was 100 times greater than that of the largest volcanic eruption in recent history , the 1815 eruption of Mount Tambora in Indonesia , which caused the 1816 " Year Without a Summer " in the Northern Hemisphere . Toba 's erupted mass deposited an ash layer of about thick over the whole of South Asia . A blanket of volcanic ash was also deposited over the Indian Ocean , the Arabian Sea , and the South China Sea . Deep-sea cores retrieved from the South China Sea have extended the known reach of the eruption , suggesting that the calculation of the erupted mass is a minimum value or even an underestimate
Year Without a Summer
Year Without a Summer
Toba catastrophe theory