- USGS PHOTO GLOSSARY OF VOLCANIC TERMS
Magma contains dissolved gases that are released into the atmosphere during eruptions. Gases are also released from magma that either remains below ground (for example, as an intrusion) or rises toward the surface. In such cases, gases may escape continuously into the atmosphere from the soil, volcanic vents, fumaroles, and hydrothermal systems. The most common gas released by magma is steam (H2O), followed by CO2 (carbon dioxide), SO2 (sulfur dioxide), (HCl) hydrogen chloride and other compounds.\Photograph by K.A. McGee on 19 September 1995Sulfur dioxide and other volcanic gases rise from the Pu`u `O`o vent on Kilauea Volcano, Hawai`i. During periods of sustained eruption from Pu`u `O`o between 1986 and 2000, Kilauea emitted about 2,000 to 1,000 metric tonnes of irritating sulfur dioxide gas (SO2) gas each day.
Glossary of volcanic terms. - University of Wisconsin Oshkosh. G. J. Hudak. 2001.
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Volcanic gas — Volcanic gases include a variety of substances given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating… … Wikipedia
volcanic ash — USGS PHOTO GLOSSARY OF VOLCANIC TERMS Volcanic ash consists of rock, mineral, and volcanic glass fragments smaller than 2 mm (0.1 inch) in diameter, which is slightly larger than the size of a pinhead. Volcanic ash is not the same as the soft… … Glossary of volcanic terms
volcanic dome — USGS PHOTO GLOSSARY OF VOLCANIC TERMS Volcanic domes are rounded, steep sided mounds built by very viscous magma, usually either dacite or rhyolite. Such magmas are typically too viscous (resistant to flow) to move far from the vent before… … Glossary of volcanic terms
Volcanic Explosivity Index — USGS PHOTO GLOSSARY OF VOLCANIC TERMS The Volcanic Explosivity Index, or VEI, was proposed in 1982 as a way to describe the relative size or magnitude of explosive volcanic eruptions. It is a 0 to 8 index of increasing explosivity. Each increase… … Glossary of volcanic terms
Gas — This article is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas (disambiguation). Ga … Wikipedia
Volcanic ash — consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions,United States Geological Survey. [http://volcanoes.usgs.gov/Hazards/What/Tephra/tephra.html Tephra: Volcanic Rock and Glass Fragments.] Retrieved… … Wikipedia
Volcanic rock — is an igneous rock of volcanic origin. Texture Volcanic rocks are usually fine grained or aphanitic to glassy in texture. They often contain clasts of other rocks and phenocrysts. Phenocrysts are crystals that are larger than the matrix and are… … Wikipedia
Volcanic cone — Puʻu ʻŌʻō, a cinder and spatter cone on Kīlauea, Hawaiʻi Volcanic cones are among the simplest volcanic formations. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volc … Wikipedia
Volcanic Explosivity Index — The Volcanic Explosivity Index (VEI) was devised by Chris Newhall of the U.S. Geological Survey and Steve Self at the University of Hawaiokinai in 1982 to provide a relative measure of the explosiveness of volcanic eruptions. Volume of products,… … Wikipedia
Volcanic glass — A sand grain of volcanic glass under the petrographic microscope. Its amorphous nature makes it go extinct in cross polarized light (bottom frame). Scale box in millimeters. Volcanic glass is the amorphous (uncrystallized) product of rapidly… … Wikipedia