27
November 2003
What makes volcanoes explode?
A fundamental problem in volcanology is the nature of the transition from effusive to explosive eruption. In an effusive eruption, lava flows out, with little explosive activity. Fragmentation of magma, the molten material under the Earth's crust, is considered a defining characteristic of explosive eruptions, and occurs when viscous stresses exceed the magma's tensile strength. Not so simple. Work on obsidian (a volcanic glass) from Big Glass Mountain, California, shows that magma fragmentation does not necessarily cause explosive volcanism. It occurs in association with shear along the conduit walls in both non-explosive and explosive eruptions.
Explosive volcanism may not be an inevitable
consequence of magma fragmentation
HELGE M. GONNERMANN & MICHAEL MANGA
Nature 426, 432–435 (2003); doi:10.1038/nature02138
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