EARTH 119 Chapter Notes - Chapter 9: Hyaloclastite, Magma Chamber, Terrestrial Planet
16 Oct 2016
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Earth 119- chapter 9: the wrath of vulcan: volcanic eruptions. Lava viscosity depends on composition and temperature. Basaltic lava has low viscosity and can flow far, but rhyolitic lava is so sticky that it forms a dome-like mass above the vent. Volcaniclastic deposits (aggregates of volcanic debris) include pyroclastic debris erupted directly from a volcano, and volcano-sedimentary material that moved since initial deposition, commonly in the presence of water. Ash is very fine, lapilli is marble-sized, and blocks and bombs are bigger. Such material may fall from eruptive clouds or may rush down the flank of a volcano in a pyroclastic flow. Lahars consists of a slurry-like mixture of volcanic debris and water, which can travel far. Volcanoes can emit gas, some of which is trapped as bubbles within lava. A magma chamber lies in or below a volcano. Molten rock rising from this chamber erupts at a vent. Some vents are chimney-like and others are long fissures.
