I just watched Secrets of the Dead (episode “Catastrophe”, which was fantastic, by the way) which illustrated the devastating global consequences of a massive volcanic eruption.
As far as I know, there is no way to really accurately predict or mitigate volcanic eruptions. I know this is pretty ludicrous, but what if particularly dangerous volcanoes were sort of popped the way one does with acne - basically, creating a let-off valve so the lava/etc could just sort of ooze out over a long period of time instead of building up to an explosion (and sending massive quantities of ash into the air, obscuring the sunlight to a degree and causing significant temperature drop/inadequate crop growth/drought, etc)?
I imagine this is a really stupid, unfeasible idea, but I’d like to know exactly why. Too far a distance to have to drill through? Inability to create an adequate sized tunnel? Not enough space to accommodate all the resulting lava? Too much of the Earth’s innards leaking out and, I don’t know, messing with the distribution of the layers of the Earth?
The only technology that would even have the remotest possibility of working would be using thermonuclear weapons, and I doubt that people would like very kindly on the government detonating H-bombs in every potentially dangerous volcano.
Agreed about the nukes. Even the deepest drilling we’ve ever done isn’t deep enough to tap the magma chambers of volcanoes, and we’ve got a double problem - as you near the magma chamber, drill bits will melt. Conventional mining and explosive are just paltry efforts when compared to the size of a volcano and you’ve still got the problem of equipment melting before it can get the job done.
I think the bigger problem is that we don’t understand volcanoes very well. While it is true that some volcanoes build up pressure until a final explosive eruption, it is also true that some volcanoes literally release steam slowly and fail to erupt. Without knowing the difference between the two, we’d be as likely to cause an eruption as to minimize one.
Remember that a lot of volcanism is due to gas stored in the magma. When it is under pressure, the gas remains dissolved, but uncapping the system can be like shaking a soda can and opening it up. Thus, “old magma” that has been out-gassing for a long time is not very dangerous. Think Hawaii- it flows around, burns up some trees and houses and then cools. “New magma” that is still full of gas is violently explosive. Think Mt. St. Helens or Krakatoa - it might blow itself up so completely that you no longer have a volcano.
All magmas are not the same. The magma in explosive eruptions is not the same as in the runny basalt eruptions you see in Hawaii, but is much more viscous andesites and rhyolites. The magma composition is what determines what kind of eruption will occur (explosive vs. runny effusive) and so there is no way you are going to tunnel into a rhyolite magma chamber and get anything oozing out.
What I see happening in the H-bomb scenario is that you blow the top off a volcano, the magma that’s in the feeder dykes erupts, but the dykes themselves would rapidly solidify and clog because of the removal of the pressure of the overlying rocks. The net result would be very little relief of the heat and pressure in the actual magma chamber. You would need a huge H-bomb to get deep enough to relieve the pressure in the chamber itself and the result would probably be just the kind of catastrophic eruption you’re trying to prevent.
