Could we control volcanoes with pressure vavles.almost lie casey jones letting off steam,blowing the whistle?

Err No!





Even if we assume that we have the technology to drill into the top of a very hot, highly-pressured molten magma chamber (which we don't!) the idea is still an incredibly bad one. Magma chambers under volcanoes contain a great deal of hot gas and water vapour effectively held in solution under great heat and pressure. If you release the pressure at the top of the magma chamber, the gas will expand enormously (imagine unkorking a really large hot champagne bottle). The basic gas laws of physics tell you that a sharp reduction of pressure will be accompanied by a huge (several orders of magnitude) increase in volume. Any ';pressure valve'; could never contain something like this; the top of the magma chamber would fracture, and the resulting eruption would be catastrophic, likely destroying the volcano and surrounding area too. To quote an earlier answerer: ';Kaboom!';.





A similar, albeit much smaller scale catastophe has occasionally occured when drilling for oil and gas in highly over-pressured reservoirs. Should bad drilling techniques result in the fracturing of the topseal to a reservoir, the result would usually be the destruction of the drilling rig and the loss of all life on board.





Still - it's nice to be reminded of ';Casey Jones';!!!Could we control volcanoes with pressure vavles.almost lie casey jones letting off steam,blowing the whistle?
Two pretty much insurmountable problems to your proposed solution:





1. The engineering challenges are extremely daunting, not even sure the materials exist to build devices in or near molten rock.





2. The way really violent volcanic eruptions occur, is when pressure on a magma reservoir is RELEIVED, and then all the gas in solution in the magma turns into gas. Kaboom. (That's simplified too.)





In other words volcanic eruptions aren't really caused by pressure quite the way you are thinking. Phreatic steam explosions might be prevented with your method, but those are small and rare, not worth the trouble.Could we control volcanoes with pressure vavles.almost lie casey jones letting off steam,blowing the whistle?
NO THEY WOULD EXPLODE!!!!