How much energy in a volcanic eruption?
]Volcanoes also release mind-boggling quantities of energy, though usually not quite on the scale of hurricanes (thankfully for those who live near!). But if we look at a well-known major volcanic eruption, the eruption of Mount St. Helens in 1980, we find that: "In all, Mount St. Helens released 24 megatons of thermal energy, 7 of which was a direct result of the blast. This is equivalent to 1,600 times the size of the atomic bomb dropped on Hiroshima" (U.S. Geological Survey).
But Mount St. Helens wasn't even at the top of the scale of Volcanic Explosivity Index. It was a class 5, and the scale goes up all the way to 8, which are called "mega-colossal" eruptions. These class 8 super-volcanos erupt extremely rarely (otherwise we wouldn't be here), but when they do, more than 1,000 cubic kilometers of rock and ash are ejected, the climate of the whole planet is affected for extended periods of time, and mass-extinctions can be expected. Now that is powerful! To get anywhere close to that kind of energy release, the U.S. and Russia would have to use their entire nuclear arsenals simultaneously, and even that might not be enough to compare depending on how long the volcanic eruption lasts.