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Topic: Volcanic vent

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	Volcano -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-10)
		Volcanism has been proposed as a mechanism for the replenishment of the dense atmosphere of the (additional info and facts about Saturnian) Saturnian moon ((Greek mythology) any of the primordial giant gods who ruled the Earth until overthrown by Zeus; the Titans were offspring of Uranus (Heaven) and Gaea (Earth)) Titan.
		Volcanic activity now releases about 130 to 230 teragrams (145 million to 255 million (A United States unit of weight equivalent to 2000 pounds) short tons) of (A heavy odorless colorless gas formed during respiration and by the decomposition of organic substances; absorbed from the air by plants in photosynthesis) carbon dioxide each year.
		Volcanic action was often attributed to chemical reactions and a thin layer of molten rock near the surface.
	www.absoluteastronomy.com /encyclopedia/v/vo/volcano.htm (4203 words)

	Volcanic cone - Wikipedia, the free encyclopedia
		Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption.
		Explosive eruptions from a vent where the magma is interacting with groundwater or the sea (as in an eruption off the coast) produce steam and are called phreatic.
		A cinder cone is a volcanic cone built almost entirely of loose volcanic fragments called cinders (pumice, pyroclastics, or tephra).
	en.wikipedia.org /wiki/Volcanic_cones (463 words)

	Volcanic ash - Wikipedia, the free encyclopedia
		Volcanic ash is the term for very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent.
		Unlike the ash that forms from burning wood or other combustible materials, volcanic ash is hard and abrasive, rather than soft and fluffy.
		Volcanic ash is not poisonous, but inhaling it may cause problems for people whose respiratory system is already compromised by disorders such as asthma or emphysema.
	en.wikipedia.org /wiki/Volcanic_ash (718 words)

	Volcanic and Geologic Terms
		Central Vent: A central vent is an opening at the Earth's surface of a volcanic conduit of cylindrical or pipe-like form.
		Hot Spot: A volcanic center, 60 to 120 miles (100 to 200 km) across and persistent for at least a few tens of million of years, that is thought to be the surface expression of a persistent rising plume of hot mantle material.
		Volcano: A vent in the surface of the Earth through which magma and associated gases and ash erupt; also, the form or structure (usually conical) that is produced by the ejected material.
	volcano.und.nodak.edu /vwdocs/glossary.html (4560 words)

	Volcano - Wikipedia, the free encyclopedia
		A large number of minor and trace gases are also found in volcanic emissions, for example: hydrogen, carbon monoxide, and volatile metal chlorides.
		Volcanic activity now releases about 130 to 230 teragrams (145 million to 255 million short tons) of carbon dioxide each year.
		Volcanic eruptions may inject an aerosol of particles and chemicals in the Earth's atmosphere.
	en.wikipedia.org /wiki/Volcano (3658 words)

	USGS Photo Glossary: Volcanic vent
		Small lava fountain erupts from a new vent on the flank of Pu`u `O`o spatter and cinder cone on the east rift zone of Kilauea Volcano, Hawai`i.
		Vents are openings in the Earth's crust from which molten rock and volcanic gases escape onto the ground or into the atmosphere.
		Vents may consist of a single circular-shaped structure, a large elongate fissure and fracture, or a tiny ground crack.
	volcanoes.usgs.gov /Products/Pglossary/vent.html (120 words)

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		By this definition, volcanic particles are deposited as sediments, the principal differences with nonvolcanic sediments being in some of the physical processes by which the particles are formed.
		Volcanic epiclasts are clasts of volcanic composition derived from erosion of volcanoes or ancient volcanic terrains.
		Volcanic ash is composed of vitric, crystal or lithic particles (of juvenile, cognate or accidental origin) of various proportions.
	volcanology.geol.ucsb.edu /frags.htm (972 words)

	Selected Volcano Terms, Long Valley area, California
		Volcanic rock (or lava) characteristically medium dark in color and containing 54 to 62 percent silica and moderate amounts of iron and magnesium.
		Volcanic rock (or lava) that characteristically is dark in color, contains 45 to 54 percent silica, and is rich in iron and magnesium.
		Volcanic rock (or lava) that is intermediate in composition between rhyolite and dacite.
	lvo.wr.usgs.gov /Terms.html (287 words)

	CVO Menu - Miscellaneous Volcanic Facts
		People use volcanic products, the internal heat associated with young volcanic systems has been harnessed to produce geothermal energy, and most of the metallic minerals mined in the world, such as copper, gold, silver, lead, and zinc, are associated with magmas found deep within the roots of extinct volcanoes.
		Volcanic domes are masses of solid rock that are formed when viscous lava is erupted slowly from a vent.
		During many volcanic eruptions, fragments of lava or rock are blasted into the air by explosions or carried upward by a convecting column of hot gases.
	vulcan.wr.usgs.gov /LivingWith/VolcanicFacts/misc_volcanic_facts.html (5674 words)

	[No title]
		The phrase "suspected volcanic activity" used to characterize several responses, refers to an eruption report or a report of unusual activity that is subsequently determined to be normal or enhanced fumarolic activity, weather-related phenomena, or a non-volcanic event.
		Lava flow from west vent is visible incising the snow and ice mantle of the cone.
		As the plane passes over the volcano, the active vent was visible as a secondary crater against the inner wall of the main summit crater which appears to be formed by coalescence of several separate steep-walled pits.
	geopubs.wr.usgs.gov /open-file/of97-433/1996summary.txt (7252 words)

	Glossary (Site not responding. Last check: 2007-10-10)
		Volcanic bombs undergo widely varying degrees of aerodynamic shaping, depending on their fluidity, during the flight through the atmosphere.
		The flowing mixture of water and debris (intermediate between a volcanic avalanche and a water flood) that forms on the slopes of a volcano.
		A vent (opening) in the surface of the Earth through which magma erupts; it is also the landform that is constructed by the erupted material.
	t3.preservice.org /T0211429/thinkquest/glossary.htm (3101 words)

	Volcanic and Seismic Hazards on the Island of Hawaii: Volcanic Hazards
		Most volcanic eruptions produce fragments of lava that are airborne for at least a short time before being deposited on the ground.
		Any hazard posed by volcanic gases is greatest immediately downwind from active vents; the concentration of the gases quickly diminishes as the gases mix with air and are carried by winds away from the source.
		Ground cracks and settling are commonly associated with volcanic activity; both generally occur near active or recently active volcanic vents as the result of shallow underground movement of magma.
	pubs.usgs.gov /gip/hazards/hazards.html (2695 words)

	Volcanic and Geologic Terms \| Taken From Volcano World
		Central Vent: A central vent is an opening at the Earth's surface of a volcanic conduit of cylindrical or pipelike form.
		Dacite: Volcanic rock (or lava) that characteristically is light in color and contains 62 to 69 percent silica and moderate a mounts of sodium and potassium.
		Renewed volcanism stage: Refers to a stage in the evolution of a typical Hawaiian volcano during which, after a long period of quiescence, lava and tephra erupt intermittently.
	www.ferndale.wednet.edu /nb/facts/maps/baker/glossary.htm (4320 words)

	CVO Menu - Glossary of Volcano and Related Terminology
		An vent or opening in the ground from which hot water vapor (steam) and (or) volcanic gases are emitted.
		Volcanic gas emissions, that may be accompanied by a change in the temperature of the gases or fluids emitted.
		Scoria is a vesicular (bubbly) glassy lava rock of basaltic to andesitic composition ejected from a vent during explosive eruption.
	vulcan.wr.usgs.gov /Glossary/volcano_terminology.html (6091 words)

	Volcanic and Geologic Terms Glossary
		Basalt: Volcanic rock (or lava) that characteristically is dark in color, contains 45 to 54 percent silica, and generally is rich in iron and magnesium.
		Dacite: Volcanic rock (or lava) that characteristically is light in color and contains 62 to 69 percent silica and moderate amounts of sodium and potassium.
		Somma: A circular or cresent-shaped ridge that is steep on its inner side and represents the rim on an ancient volcanic crater or caldera.
	volcano.und.nodak.edu /vwdocs/msh/llc/is/vgt.html (1838 words)

	Lo'ihi Underwater Volcanic Vent Mission Probe
		An instrumented underwater probe, built at the Jet Propulsion Laboratory, to examine deep, hydrothermal vents at the Lo'ihi Seamount, 27 km (20 miles) east of the Big Island of Hawaii at a depth of about 1,300 meters (4,250 ft).
		A long-term objective of JPL engineers is to develop instruments for a probe that could be used to search for life in the underground oceans that may exist on Jupiter's moons, Europa and Callisto.
		Following the success of this mission, it is planned to add an ultraviolet camera (for imaging organic matter) and a sensor to detect chemicals used by microbes in the vicinity of undersea vents to generate energy.
	www.daviddarling.info /encyclopedia/L/Loihi.html (343 words)

	Pele - Io: Jupiter’s Volcanic Moon
		Its plume is nearly invisible, except in back-lit photographs, and it is thought to be an example of a stealth plume.
		Stealth plumes occur when the sulfur dioxide gas in the volcanic vent is at a very high temperature.
		Upon being expelled from the vent, the gas rapidly expands resulting in an undetectable, high-velocity jet of cold gas from which no snow is produced.
	www.planetaryexploration.net /jupiter/io/pele.html (425 words)

	Volcanoes: Principal Types of Volcanoes
		As the cone is stripped away, the hardened magma filling the conduit (the volcanic plug) and fissures (the dikes) becomes exposed, and it too is slowly reduced by erosion.
		As volcanic activity continues, perhaps over spans of hundreds of years, the cone is built to a great height and lava flows form an extensive plateau around its base.
		All that remains is a projecting plug or "volcanic neck," a small lava-capped mesa, and vestiges of the once lofty volcano and its surrounding lava plateau.
	pubs.usgs.gov /gip/volc/types.html (1544 words)

	What is volcanic ash? (Site not responding. Last check: 2007-10-10)
		The usually violent nature of an eruption involving steam (phreatic eruption) results in the magma and perhaps solid rock surrounding the vent, being torn into particles of silt to sand size.
		A layer of volcanic ash tends to become cemented together (see pozzulana) to form a firm rock called tuff (pronounced "toof").
		This is known as an "ash fall." The term for any material explosively thrown out from a vent is ejecta or pyroclastic debris.
	www.juiceenewsdaily.com /0505/news/ash_vol.html (615 words)

	Vic Camp - Volcano Types
		A volcanic vent is an opening exposed on the earth's surface where volcanic material is emitted.
		The central vent is connected at depth to a magma chamber, which is the main storage area for the eruptive material.
		Because volcano flanks are inherently unstable, they often contain fractures that descend downward toward the central vent, or toward a shallow-level magma chamber.
	www.geology.sdsu.edu /how_volcanoes_work/Volcano_types.html (555 words)

	Volcanic Phenomena at Pompeii
		The pyroclastic flows of the Peléan phase at Pompeii were the primary cause of volcanic damage to walls, however the air-fall pumice and ash fall during the Plinian phase was also significant since the deposits collapsed roofs and buried low structures, shielding them from the effects of the pyroclastic flow that followed.
		The key basis for distinction is the amount and nature of the pyroclastic material included in the mixture of volcanic solids and gas.
		The deposits reveal that the city was hit first by a pyroclastic surge, leaving a deposit of 10 to 20 cm, closely followed by a pyroclastic flow that left a deposit varying in thickness from 200 cm at the north wall of the city to 50 cm in the Necropolis to the south [Sigurdsson 1982].
	urban.arch.virginia.edu /struct/pompeii/volcanic.html (1301 words)

	New Scientist Breaking News - New images reveal volcanic hotspot on Mars
		The layers may be volcanic ash mixed with water ice, says Gerhard Neukum, principal investigator of the HRSC at the Free University of Berlin, Germany.
		He says his observations suggest the cones form simply by lava bubbling up from a volcanic vent, in line with leading theories of how Martian volcanoes behave.
		Neukum himself admits that his interpretation of these volcanic cones may be wrong "because we do not have any higher resolution imagery" than the 10 m resolution of the main camera on the HRSC.
	www.newscientist.com /article.ns?id=dn7089 (775 words)

	EO News: New Deep Sea Volcanic Vent Probe Tested - July 26, 1999 (Site not responding. Last check: 2007-10-10)
		Hydrothermal vents and the biological communities thriving in these remote pockets of the sea floor are found primarily at tectonic plate junctions at temperatures ranging from nearly 80 to almost 400 degrees Celsius (170 to 750 degrees Fahrenheit) and at pressures as high as 6,000 pounds per square inch.
		Typical water temperatures inside the vents range from 200 to more than 350 degrees C (392 to 662 degrees F) and drop quickly to ambient temperatures of about 4 degrees C (39 degrees F) outside of the vents.
		The Tahiti underwater volcanic vent mission is a collaboration of the international POLYNAUT campaign in the South Pacific, conducted by the French Institute of Research and Exploitation of the Sea, with involvement from the University of Hawaii and NASA/JPL.
	eobglossary.gsfc.nasa.gov /Newsroom/NasaNews/1999/19990726645.html (878 words)

	COMPUTATIONAL IDENTIFICATION OF VOLCANIC VENT ALIGNMENTS IN THE PACIFIC NORTHWEST (Site not responding. Last check: 2007-10-10)
		A promising technique for unbiased identification of vent alignments is the Hough transform method (Wadge and Cross, 1988).
		This technique is sensitive to the shape of the field and the density of vents, with elongate fields and high vent density resulting in some spurious alignments.
		The alignments are subsequently filtered for the number of vents, spacing between vents, and correlation (also specified by the user).
	gsa.confex.com /gsa/2002AM/finalprogram/abstract_43766.htm (482 words)

	Volcanic rocks - Lab #2 (Site not responding. Last check: 2007-10-10)
		Evolution of the Eocene-Paleocene North Atlantic; the Miocene Pacific Northwest: There is evidence for a period of extensional volcanism associated with hotspot activity at about 60 Ma in the vicinity of Iceland in the North Atlantic region.
		Exposed inner walls of Crater Lake caldera with alternating andesite lava (red-purple-gray) and pyroclastic ash (buff or yellowish) typical of the construction of andesite stratavolcanoes.
		Oregon and California Examples: Vented domes of dacite and rhyolite tend to develop along the caldera rim, or along radial and/or concentric faults centered on the central volcanic vent late in the eruptive history of Cascade andesite and basaltic andesite volcanoes.
	darkwing.uoregon.edu /~dogsci/kays/313/volcaniclab.html (1188 words)

	Active volcanic vent on Mars? (Site not responding. Last check: 2007-10-10)
		If the dark material constitued some sort of material vented from within the crater, or even material blown out of the crater by the wind, this area should also be covered with dark material.
		The volcanic regions of Mars, by contrast, tend to be somewhat lighter in albedo than these darker areas.
		Another key characteristic of a vent or geyser I consider to be the fact that the origin is quite small compared to the widest portion of the dark area.
	www.science-one.com /new-453040-4253.html (15474 words)

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