No, it's not like a balloon, an eruption isn't the earth popping, it's an upheaval from the mantle eventually surfacing through a weak spot that causes it.
"an upheaval from the mantle eventually surfacing through a weak spot" sounds like a more technical way of saying "the earth popping like a balloon". I'm prepared to believe there are differences but your explanation doesn't really convey them to me.
> Drilling into, or above, the magma chamber below Yellowstone would be fraught with problems. For one, it could potentially cause the volcano to erupt, the very thing we’re trying to avoid.
I, for one, am pretty sure the article is wrong there. What I've heard from geologists is that Yellowstone's magma chambers simply are not molten enough to erupt.
Given that eruptions are primarily driven by the ejection of gas, the “earth popping like a balloon” analogy is more apt than you think it is (even if it's not exactly like that, and more like opening a shaken bottle of Champaign after you won the Grand Prix).
Are they "primarily driven by the ejection of gas" or more accurately preceded by gas and steam as the magma itself is gas rich and thermo and fluid dynamics dictate the gas will be at the vanguard of the breach?
The magma, like Champaign, is indeed gas rich, and when the pressure lowers, the gas is released and wants to go away, carrying lots of material with it, be it Champaign, rock or lava, that's how you get the projections (the eruption per se)
In this analogy, the needle is as big as we can make it.
Gas-rich is where the danger is, as I understand it. Those gasses expand as they get closer to the surface, and if they're trapped in viscous magma that doesn't flow easily and puts a lot of stress on the rocks above.
The fluid basaltic lavas of Hawaii don't explode, they flow out and make shield volcanos.