Volcanoes may not be fed by magma ‘mushrooms’

July 24, 2008

THE plumes of hot magma that fuel the volcanism of "hotspots" like Hawaii and Iceland have long been thought to be efficient conduits of Earth’s fiery contents. Yet it seems they can be rather lacklustre on their way to the surface.

We traditionally picture the plumes of hot magma that rise through the mantle as mushroom-shaped with a thin stalk feeding a bulbous head, or hotspot, beneath the crust. However, seismic imaging in Iceland reveals a patchy structure without a stalk, leading some researchers to suggest there are no plumes at all.

Ichiro Kumagai and colleagues at the Paris Institute of Earth Physics in France reckon they can explain these patchy structures. They created plumes by heating the base of a tank containing sugar syrups of varying densities, to simulate the composition of the mantle. The densest material was heated just enough to…

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Posted in Earth Sciences, Science and Technology