Question: what are the 20 supervolcanoes in world?
Answer: "Once you get enough melt, you can start an eruption just like that." There are about 20 known supervolcanoes on Earth - including Lake Toba in Indonesia, Lake Taupo in New Zealand, and the somewhat smaller Phlegraean Fields near Naples, Italy. Super-eruptions occur rarely - only once every 100,000 years on average.