Moving Mountain

As you wind down the week’s activity, take a moment or two to pause and admire Mount Etna, which is undergoing a spectacular series of eruptions (click for larger images).

Mount Etna

Mount Etna Mount Etna Mount Etna

Remarkable.

You can look at a live webcam and make your own snapshots like these (which are from Amara – thanks!) at this link. Who needs Friday night movies with drama like this going on live?

This all puts me in mind of the fact that the places where I spent most of my childhood were completely erased by a volcano. All gone, except in my memory and those of others. So looking at these photos gives me mixed feelings…. those of loss, and at the same time feelings of being happy to be reminded to reflect on the memories from time to time in order to keep them alive.

-cvj

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8 Responses to Moving Mountain

  1. Aaron F. says:

    Hey! I know it’s off-topic, but I just read your entry about the evacuated art class. Tough luck! Did you manage to get any new students before the drop/add deadline?

  2. Clifford says:

    Hi,

    Thanks for asking. I’ll let you know when I know. It is touch and go right now. I am curious: Why did you not ask the question in the comment thread of the post the question is about? Then it would not be off-topic… Do tell.

    -cvj

  3. Amara says:

    Clifford:
    Hmm, Monserrat volcano? Probably if volcanoes destroyed my home I might have similar mixed feelings. The volcanoes that were part of my life since I was a kid, fortunately never did that.

    I think Mt. Etna has taken on a personality for me that is similar to what the Sicilians feel. When I first saw photographs of Mt. Etna, I needed to write poetry. I think some talented person should make music out of the must-hear-to-believe lava flow or rockfall sounds. Oh what a symphony of sights and sounds these volcanoes give! After these years (but only two visits), It’s a ‘she’ with many moods and maybe soon I will be able to ‘read’ her moods like the local people.

    Usually when I face Etna, she invokes my nonscientific side, and I’m struck with her beauty. When I override that, and invoke my scientific side, however, the following thoughts come to mind.

    In these volcanoes, we are literally witnessing the energy left from the formation of the Earth and the subsequent meteoritic impacts and radiogenic decay. Earth is the only terrestrial planet using the plate tectonics mechanism to relieve itself of internally-generated heat. Since the other terrestrial planets also have differentiated layers with the same need to cool off, I think that it’s remarkable that Earth’s method to cool off uses such a ‘cool’ combination of conduction and convection and advection; in particular, the crust plus lithosphere move quasi-rigidly and transfer heat via conduction while those individual plates float over a partially molten (and convective) outer mantle, all of which gives us the restless Earth that we know and love.

    On Earth, there are several types of volcanic eruptions that release gases to the atmosphere: those at mid-ocean ridges, and those at subduction zones, where volatile-rich sediments from the ocean floor are pulled beneath the continents and melted. In between are hot spot volcanoes. “Ocean island basalts”, or OIBs, are formed by the decompression of deep mantle plumes under hot spots; the plumes effectively cool the Earth’s core. Hot spots are usually associated with volatile gases from deeper mantle zones. At mid-ocean ridges, since many of the interior’s volatiles were released during core formation, the volatile gas content of mid-ocean-ridge basalts (MORBs) is relatively low. By contrast, volcanism at subduction zones recycles volatile gases from the sea floor back into the atmosphere, and due to trapped bubbles released under pressure, subduction zone volcanoes can show explosive behavior.

    Etna is usual because you can see almost all of those kinds of behavior. It is the largest continental volcano in Europe and, by far, the most active. The summit vents are degassing or exploding almost constantly, and every few years, lava eruptions occur from the lower flanks. According to Boris Behncke, for the last 100,000 years, Etna has been gradually assuming the character of a subduction volcano (between the African and Eurasian tectonic plates), but with the addition of a counter-clockwise rotational “twist” on its plate, which weakens further the crust under Etna. To the present time, Etna has been fed by a “hot-spot”, such that under Hawaii, but now its magma is more gas-rich. The more gas-rich the magma, and the more ground-water is involved, the more explosive generally is the eruption, with the most explosive type called: a “phreato-magmatic” eruption, where groundwater steam fragments the magma.

    You see, whichever way you choose to face Etna, she has something interesting to offer to you!

  4. Amara says:

    “Etna is usual” –> Etna is unusual. (correction)

  5. Jude says:

    I’m such a sucker for volcano photos. Thanks for posting this, because it inspired me to go to Volcano World, where I noticed that they have an RSS feed for current eruptions.

    When I was 7, I read a book about volcanoes which made me frightened to live in the mountains of Colorado. It would have helped if someone had explained to me the difference between igneous, metamorphic, and sedimentary rocks. Colorado has mountains and hot springs, but only one recent volcano at Dotsero.

  6. Aaron F. says:

    I am curious: Why did you not ask the question in the comment thread of the post the question is about? Then it would not be off-topic… Do tell.

    Oh… I hadn’t read the post until long after it was posted, so I figured that you probably wouldn’t be checking it for comments anymore, and decided to put my comment somewhere it was more likely to be read.

  7. Clifford says:

    Hi, you don’t need to do that. If you look on the sidebar, there is a “recent comments” menu. I can see recent comments on any post, whenever they took place. Sticking comments near the posts that they are relevant to is also useful for later. I can go back and see what people said on a particular topic.

    Cheers,

    -cvj

  8. Aaron F. says:

    Ohhhhh, I get it! What a great idea! 🙂 *forehead slap*