Question: What is the most powerful volcano in the world which is still active and when will it next erupt?

Natasha Dowey answered on 4 Mar 2019:

This is a difficult question. It is very difficult to predict volcanic eruptions, and to predict the power of any particular eruption. First of all, it’s important to note that right now, about 40 volcanoes around the world are erupting (https://volcano.si.edu/gvp_currenteruptions.cfm). Eruptions aren’t unusual- they’re just the planet’s way of cooling down.

As for power, there is a “volcanic explosivity index” or VEI, which is a bit like the Richter Scale for earthquakes, but for volcanoes. We use it to compare eruptions and understand them a bit better. Some eruptions may have a dramatic impact on life and even climate (such as the Mount St Helens eruption in 1980, or the Pinatubo eruption in 1992), but on this scale they are actually tiddlers in terms of power.https://en.wikipedia.org/wiki/Volcanic_Explosivity_Index#/media/File:VEIfigure_en.svg

In the past, the most explosive and powerful eruptions on this VEI scale have been from ‘calderas’- these are bowls in the ground that have formed as a huge amount of magma was erupted from the crust. The Yellowstone caldera in the USA had an eruption 600 thousands years ago which is believed to have erupted more than ONE THOUSAND kilometres cubed of magma (to put into perspective, Mount St Helens only erupted ONE kilometre cubed in 1980). Yellowstone is not extinct, and clearly if it were to erupt again it would be a world-changing event. However, it is impossible to precisely know when this will happen.