Volcanoes are the bad boys (girls? but Vulcan was a male deity!) of the geological world. How bad? Pretty darn! And pretty scary. And pretty cool. And pretty.... just pretty!
I know we can all pile on Bobby Jindal (ewwww), but all the talk of volcanoes here has led me to reminiscences of volcanoes seen and hot baths enjoyed, of scary books read and Golden Books appreciated. Here are a few thoughts about eruptions, a couple of book recommendations, and some pretty pics. Just because. Mount Redoubt will never match the fury of volcanoes elsewhere, and it is unlikely it will have the impact on the earth's weather. The worst eruptions (for impact outside the immediate area) are in the equatorial regions because (from what I understand, not being a meteorologist) the wind patterns guarantee greater dispersion of the ejecta from a volcano that erupts nearer the equator.
Gunung Sibayak, pictured above the fold, is one of many volcanoes in Indonesia. It is a stratovolcano, made up of layers of rather stiff layers, and they are common at subduction zones, plate boundaries where one plate dives under another. The eruptions of these subduction-zone stratovolcanoes tend to be more violent and explosive because the magma inside of them is too stiff to allow gases to escape easily. The violence of the eruption is connected with the height of the spewing ejecta. The largest eruption in the lifetime of most of us was the eruption of Mt. Pinatubo, a subduction zone stratovolcano in the Philippines (the only larger one in the 20th century was in 1912). It erupted 10 cubic kilometers of magma and 20 million tons of Sulfur Dioxide into the atmosphere. Although it lowered the earth's temperature about 1 degree Fahrenheit, it only lasted a year and a half in its effects. Not much of a blip in volcanic eruptions.
Perhaps the most violent eruption ever in human (pre-)history, far larger than the 2.1 million years ago eruption of the Yellowstone caldera, was the eruption of Mount Toba in Indonesia. The largest eruption in the past 25 million years took place in Indonesia, leaving behind a lake easily visible from space, with a large island in its middle. In comparison with Mt. Pinatubo, or Tambora (in 1815, with 100 cubic km of ejecta, which was enough to cause the "Year Without a Summer" as far away as New England), Toba ejected an estimated 2500-3000 cubic kilometers of debris and gases into the atmosphere. Toba's eruption wasn't that long ago, in geologic time. And in addition to an "ice age" that lasted a millenium, and ash deposits that were as thick as 6 meters in India and 9 in Malaysia, this volcanic eruption seems to have caused the almost complete extinction of the human evolutionary line. You and me and everyone in the world seem to be descended from a very small group of humans (perhaps fewer than 10,000 adults) who lived between 50,000 and 100,000 years ago. Wikipedia helpfully directed me to an abstract of the initial publication of this research.
When I traveled to Indonesia on a Fulbright-Hays program in 2004, I was thrilled to visit Lake Toba. I am disappointed that I didn't pick up a rock when I was there (I sometimes remember to do that, but I was so enthralled with the locally-produced textiles that I forgot the rocks!), but I did get some stunning photographs. At the time I was taking both digital and film images. I haven't looked at the film ones in a while, but here is an image of the side of the caldera:
And this is the slope of Samosir Island, the largest island on an island anywhere in the world, and the fifth largest lake island as well:
I went looking for a Golden Book that would have been around in the late 1960s/early 1970s, when I first fell in love with the concept of volcanoes and earthquakes. Of course they are hard to find. You see, when I first read about them, we of course knew there was a "ring of fire," but other than its location very few people understood the mechanics of plate techtonics. My mother spent the later 1970s trying to understand the concept, as it was hard for her to believe/accept. She now, of course, has a tshirt she loves: "Reunite Gondwanaland" and has no problems with the idea any more. She was a geology geek, having grown up in Nevada with a father who had invested in potential mines, etc., but never had any that panned out (sorry about the pun). I am a geology geek as well; I have a strike map from 1902 on my wall; we found it when cleaning out my aunt's house after she died and I framed it as a part of family history and a really cool artefact. I did two full years of geology at college, and loved it. If I had taken chemistry at some point earlier I might have done a double major with archaeology, but there was too much basic science to pick up and graduate in the 2 years I had left after I finished the class I had enjoyed so much.
Perhaps (probably) because of the wonderful books I read about Herculaneum and Pompeii (destroyed by Vesuvius, in Italy of course) and Krakatoa (also in Indonesia) and Martinique's Mount Pelée, which erupted in 1902, killing over 30,000 people, making it the most deadly volcanic eruption of the century, I have spent a lot of time reading about disasters (this is where my fascination with the Titanic also comes in, I suppose). I have a large collection of books about earthquakes and volcanoes.
So if you want to read about volcanoes, I can recommend some good stuff.
The eruption on Martinique and La Soufrière, on the nearby island of St. Vincent (which started just a couple of hours before the more deadly Mount Pelée disaster) are the subject of La Catastrophe (in English, not in French, despite the title). I knew vaguely of La Soufrière on St. Vincent, but it had gotten mixed up in my mind with the Martinique event, where the story has it only one person survived in the town of Saint-Pierre (not quite completely true that he was the only one, but pretty impressive nonetheless that he survived). The other really good volcano book I have read in the last several years is Krakatoa: The Day the World Exploded: August 27, 1883. I have yet to see any particularly good volcano film ("Krakatoa, East of Java" starts with the geographical issue that Krakatoa is actually WEST of Java, and goes downhill from there). But I would love a recommendation for a good film about a volcano, or a new volcano book.