The largest eruption in modern times, the 1980 eruption of Mount St. Helens, was a 5 on the index. The Oruanui eruption of the Taupo Volcano in New Zealand was the world’s largest known eruption in the past 70,000 years was an 8. Another eruption of the Taupo volcano happened about 1,800 years ago. It was the most violent eruption in the world in the last 5,000 years. Mt Tambora was a 7 on the Volcanic Explosivity Index.