Active volcanoes / Aktive vulkaner:
I'm learning - that's why I'm also asking....

During the summer of 1999 I decided to learn more about WHAT volcanoes are, and what made them xxxx from time to time.. And I did not get far before I met the xxxx 'plate-tectonics'.
What's that again?'. Well, that was the definite fact that our Earth consisted of quite a few plates, upon which the continents were floating around, again upon something else further down in the deep.

Sounds interesting? At least it did to me. And so I began searching. Mostly on Internet, but also in my own books and encyclopedias. The result was quite confusing.. See my page: Platetektonikk???.
(PS - it's a large one, and still only in norwegian - sorry!)) The situation did not become easier when I got in touch with a 'rebell' on this theme, a professor at the university i Bergen, Norway, and received some of his thoughts about plate-tectonics.That's why I have included questionmarks after the title 'Platetetektonikk'. But what then have I learned? Actually I had to learn something while studying?

Well, to be honest, I first of all learned that I did not know much at all about this thing called volcanoes and plate-tectonics. But to get further in this story, one has to know a little more about the theory called plate-Tectonics and its history, but have to put that on another page, so this piece here won't be too long......

click on map for larger version

As shown on the map above, the earth is cut into several pieces, all borders consisting of either a crust or a subductionzone or what else it might show up to be. OK, so we are almost sure that those pieces are plates, and that some of them moves in certain directions, at the time being, about 2-12 centimeters ( 2-3 inches?) each year

We are also sure that some of them goes down under the others, in socalled subductionszones,
while others are colliding, like in a car to car crash, and they form large mountain-chains etc. Other plates moves along each other, some in opposite directions, which makes crustzones, and here we can find the larges earthquakes (California, Indonesia and recently Turky 1999), and also some of the most active volcanoes (California, Turkey???). Indonesia is the country with most volcanoes compared to its size.

But then - here comes the questions. You ought to have a subductionzone to keep kind of balance of the earth - the radiant, or the distance from the center of the Earth and to surface at the equator line or to one of the two poles, has to be constant. (xxxx km at the poles). From the spreading-zones comes up new lava, and new landmasses forms, and the plates move away from here. Subduction zones are typically deep trenches, where one of the plates dissapers downwards (usually the ocean-plate).
Deep sea trenches are found off the coasts of the Philippines, Japan, Indonesia and Alaska. But where are the deep trenches supposed to take care of all the other plates? Look at the map below, and click to view a larger map.

Plateboundaries (+|+|+) and trenches (violet)
click for large scale

The plates are floating in certain directions, away from the spreading zones and supposed to finally
reach a subduction zone, or to collide with some other plate. That is why chains of islands, and chains of volcanoes that have popped up on top of so called hot-spots in the earths surface, is lying just like that, in chains similar to the direction of the actual plate they are a part of, with the oldest top nearest to the place where the plate is going to end up.

But somehow there are a lot of other trenches in the big oceans where nothing is happening. Nothing dissapears, and nothing comes up. At he same time there are mountain ridges coming up both here and there the more maps you can get hold of. How or what have made them drop up?

It's still a bit too difficult to understand these theories, so I'm going to continue my study.....
Any hints?

Put your opinions right down in the mail-box!

October 2004:
Since then I have listed more than 200 different volcanoes, each has its own page
here on my site. And you bet I've learned a lot. But I am still learning.
Read more about that here

 Experiences from my surfing for Volcanoes
 2004, October: I am still learning....


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