Word: magma
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...terrestrial turmoil came in 1975, when Mount Baker, a 10,750-ft. volcanic peak in northwestern Washington, began to puff and fume. Vented steam has continued to melt ice around the summit crater of the mountain, which is only 90 miles from Seattle. The Geological Survey says that rising magma in the mountain's cone may be stoking Mount Baker's internal fires. Magma is hot, melted rock from deep within the earth that fuels volcanoes and becomes visible as lava when it breaks through the crust...
...effort to divert the magma, Italy's minister of civil protection summoned a team of volcanologists. The strategy: to redirect the lava from its southward path into a wide hollow, away from inhabited areas. The specialists hoped that spreading the lava would speed its cooling, and thus slow the momentum of the flow. The diversion required the removal of a 25-ft. section in a 328-ft.-long natural wall of old lava, and was to be accomplished by precision blasting...
...shallowest quakes were originating at a depth of about 3 miles. By last summer, they were occurring only 2 miles below the surface. Roy Bailey, coordinator of the U.S.G.S.'s volcanic hazards program, suggests that the quakes were caused by the slow upward movement of a tongue of magma-the hot molten rock that forms a volcano's lava. Still another sign: the outbreak of new steam vents, or fumaroles, in the seismically active region...
...latest round of activity caught scientists by surprise. Though volcanologists have been able to predict almost to the hour when the volcanoes of the Hawaiian Islands will erupt, Mount St. Helens presents a more difficult problem for would-be prognosticators. The molten rock, or magma, underneath the Washington volcano is a thicker, silica-rich material (unlike the less viscous molten basalt of the Hawaiian chain); more pressure must build up before the hot gases trapped within it are released. Thus the mountain erupts infrequently and violently...
According to their scenario, some of the molten rock from the subterranean cauldron of magma under the mountain will slowly be forced upward, like toothpaste being squeezed out of a tube. It will push through the vents in the "plug" of debris within the volcano's throat and emerge as lava. When it is finally exposed to the air, the lava will harden rapidly; it will probably not have enough volume or velocity to overflow the volcano's rim. Instead, as it solidifies, it will likely form a dome or cap over the vents. Eventually the dome should...