Prior eruptions have had a Volcanic Explosivity Index (VEI) of between 4 and 6 on a scale of 0 to 8. In comparison, the Eyjafjallajökull 2010 eruption had a VEI of 4. Bigger VEI-5 eruptions are comparable to Mount St. Helens 1980 eruption, while significantly rarer VEI-6 eruptions would be comparable to Krakatoa's 1883 eruption and Mount Pinatubo's 1991 eruption.