Ka-boom!

I just watched a fascinating and exciting program on NOVA, Mount St. Helen's: Back from the Dead. All about how Nature reasserted herself after the devastating eruption of May, 1980.

Part of the program had to do with the eruption itself, and with the smaller eruptions that took place over the next few years (of which I was unaware -- I don't think the media was paying much attention, since those weren't cataclysmic eruptions). Although I already had a general idea of the mechanics of a volcanic eruption -- magma being pushed up from deep underground by pressure, until the pressure is so great the magma escapes through the surface, becoming lava once it reaches the surface -- it was interesting to learn that what provides the umph to the kind of eruption at Mt. St. Helen's is water in the magma, that has becomes gas as the result of the intense heat. Actually, it seems incredible that there could be water down there in the first place...wouldn't it be too hot, I'm thinking? And where would water be coming from, 62 miles down?

The program didn't go into either question, but the good ol' Internet has informed me that water arrives deep underground when (for example) the Pacific tectonic plate is pushed under the North American plate, taking with it the water that was on top of and in the interior of the layers that are pushed down. As soon as that water hits the high temperatures of the lower depths, it becomes gas, moving up with the magma toward the surface, miles above, and contributing mightily to the ultimate bang when the surface breaks open. You could say the volcano is breaking wind!

The geologist manque in me finds all this fascinating. But what really gets me is the idea that the earth is just going about its business of evolving, just as it always has. Plates moving -- accompanied by earthquakes, tsunamis, volcanic eruptions -- causing land masses to move, inch by inch (looking at a world map you can see so clearly where South America at one time fit into the crook of Africa). These things have always happened, but now human beings are witness to their happening, thanks to the fact that there are now so many of us, living absolutely everywhere, and thanks to instant communication and satellite pictures. And because there are now so many of us, living absolutely everywhere, we are often inconvenienced by these happenings -- witness the devastation caused by the 2004 tsunami in southeast Asia, the recent earthquakes in Haiti and Chili, witness the massive shutdown of air transport with the eruption of the unpro-nounceable volcano in Iceland. But that is not the earth's concern; it is simply following the laws of its nature. As far as the earth is con-cerned we might as well not be here. And we mites (as humanoids are thought of by an alien entity in a Star Trek book I read recently) on its surface just have to run for cover when necessary. (And praying to the gods to keep the volcano from erupting ain't gonna help, either.)

There was again seismic activity at Mount St. Helen's in 2004. No eruption, no lava flow, but what the geologists call "spines" of lava were pushed up through the floor of the crater. This was truly fascinating, since in a very short period of time they were able to see these huge rock formations appear where none had existed before. But the gas that produces an explosive eruption has apparently dissipated. Until the next batch of gas-laden magma makes it slow but sure way to the surface...in 200 years? A thousand?

The earth is a hard taskmaster, but it certainly is interesting.