Researchers Fake Mini Volcanic Eruptions

"The aim was to recreate, in true-to-life detail, what happens when a volcanic eruption punches through Earth's crust."
Hugh, it seems to me the aim an excuse to play with explosives.

Especially since it DOESN'T model eruptions - especially the explosive kind.

One of the major martyrs to science is the geologist who died in the most recent explosive eruption of Mount Saint Hellens. It was known that some mountains explode, and that this was the usual mode for this volcano. But it was a big mystery HOW they exploded.

He was too close to escape when the action started. But he had a (film) camera with him. So he took a series of photos as the mountain went off, then wrapped his camera in his backpack and jacket before the devastation got to him. His camera was recovered, the film developed, and running the series of stills as a movie made the mechanism utterly clear. It was an "Of COURSE!" moment.

In this case there is a LOT of gas pressure under the mountain. This pressure, not just the buoyancy of the lava, is much of what is pushing the mountain up. Meanwhile, the weight of the mountain is what is holding the gas down, at enormous pressure.

Eventually the mountain is pushed up enough that a rock avalanche starts on one side. This releases some of the pressure, which lets the gas push the mountain up further, making it shrug much more of the side off in an enormous rock slide. One side of the mountain slides away. This leaves the gas pressure held down only by the remaining rock, which is insufficient for the task. Before the rock slide is more than about a quarter of the way down the gas is blasting the remaining rock into fine dust and launching it into the stratosphere -(as well as sideways, so goodbye neighborhood). Essentially the whole mountain goes away, leaving a crater where rebuilding the mountain for the next cycle begins.

Let's see you model THAT with explosives! (Hint: If you're throwing rocks you didn't use enough explosives.)

Lesser eruptions have a number of models, depending on things like the composition of the lava (including how much gas is bubbling out of it, like soda fizz once the lava makes it to near atmospheric pressures). Explosives don't do those justice, either.

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/dlajvQNJWCA/story01.htm

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