Asked by: Anonymous
When Mount St Helens erupted in 1980, the initial blast was equivalent to around seven megatons of TNT. That’s broadly equivalent to the yield of modern thermonuclear weapons. But the explosion that blows the top off a volcano is only a small part of the total energy released during an eruption. If you dropped a nuclear bomb into the crater of an extinct volcano, you would flatten the mountain out a bit but you wouldn’t set the volcano off because there wouldn’t be any pre-existing upwelling of magma. On an already active volcano, or one that is just about to blow, a nuclear bomb might alter the lava flow, or cause it to erupt a little sooner.
The US Army and Air Force have conducted trails with conventional bombs in Hawaii, to try and block or divert the course of individual lava flows, on numerous occasions since 1935. The results have been mixed at best. Lava is heavy, hot and very determined.