Lake Toba (Toba Caldera) was formed about 75,000 years ago by the eruption of Mount Toba (supervolcano) very severe with the scale of the eruption reached 8.0 VEI
(Volcanic Explosivity Index). These eruptions spewed more than 2000 cubic kilometers of materia. Eruption reached a height of 50 kilometers and 100 meters thick hot clouds up to 400
meters (Bill Rose and Craig Chesner, Michigan Technology University / Eastern Illision University). it is the largest known explosive eruption on Earth in the last 25 million years.
It killed most human living at the time (more than 60 percent of the human population on earth) and is believed to have created a population bottleneck in central East Africa and India which affects the genetic make up human of worldwide population to the present.
Evidence of the magnitude of the eruption of Mount Toba is the discovery of archaeological sites in India where the distirbution of a valconic ash found in
this region even though the distance is 3000 miles from the center of the eruption, volcanic ash is expected even cover up to the Arabian Sea and the South
China Sea. (Expected from various sources ).