MadSci Network: Earth Sciences

Re: Are there really Super Volcanoes?

Date: Thu Oct 26 14:59:03 2000
Posted By: Eder Molina, Researcher PhD, Dept. of Geophysics, Institute of Astronomy and Geophysics - USP
Area of science: Earth Sciences
ID: 971980090.Es

I think you are talking about "hot-spots", that are "small" conducts, with 
a few hundred kilometers in diameter, that connect the core-mantle 
boundary with the surface. This idea was initially proposed by J.T. 
Wilson, of Toronto University, and the concept was developed later by W.J. 
Morgan, of Princeton, in 1970. Tuzo's idea was the only mechanism able to 
explain the volcanic island chains in regions where you don't have a 
lithospheric plate boundary (e.g., Hawaii Islands).

The hot spots are the expression in the surface of these volcanic 
conducts, called "plumes". There are about 20 hot spots in the world, most 
of them in Africa, and one in the region of the Yellowstone Natl. Park. In 
these regions, one expect a high heat flow (with volcanism, geisers, 
etc.), and lava eruption if it is in the continent; if the hotspot is 
located in the oceanic area, as the lithospheric plate is moving, it can 
create chains of islands, just like Hawaii. In these island chains one can 
observe that in one end the volcanism is extinct and the island is older 
than the other extreme, where the volcanism is active and the island is 

An interesting reference about this theme can be found in chapter 16 
("Causes of Plate Tectonics") of the book "The way the Earth Works: an 
introduction to the new global geology and its revolutionary development", 
by Peter J. Wyllie, edited by John Wiley & Sons, Inc., 1976.

Best regards

Eder C. Molina
Dept. of Geophysics
Institute of Astronomy and Geophysics 
University of Sao Paulo - BRAZIL

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