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	Magma chamber - Wikipedia, the free encyclopedia
		A magma chamber is a chamber typically between 1 km and 10 km beneath the surface of the Earth formed as rising magma forms a reservoir if it is unable to rise any further.
		Another effect of the cooling of the chamber is that the solidifying crystals will release the gas (primarily steam) previously dissolved when they were liquid, causing the pressure in the chamber to rise, possibly sufficiently to produce an eruption.
		Thus, stratification of a magma chamber may result in an increase in the amount of gas within the magma near the top of the chamber, and also make this magma more viscous; potentially leading to a more explosive eruption than would be the case had the chamber not become stratified.
	en.wikipedia.org /wiki/Magma_chamber (514 words)

	Magma - Wikipedia, the free encyclopedia
		Magma is a complex high-temperature (between 650 and 1200 °C) silicate solution that is ancestral to all igneous rocks.
		Magma rises primarily because a melt is less dense than its source rock, it is propelled upward through the lithosphere by the buoyancy that its lower density creates (the way less dense wood is pushed up and floats in denser water).
		Magma is composed mainly of silica; alkalis (sodium, potassium, calcium, magnesium) and iron.
	en.wikipedia.org /wiki/Magma (1605 words)

	Shallow crustal magma chamber of Coaxial Segment
		This magma chamber is distinct from, and apparently unconnected to, the Axial magma chamber.
		The Coaxial magma chamber is similar in width and overall traveltime delay to the ones on the fast-spreading East Pacific Rise at 9.50°N (Toomey et al., 1990) and at 13.00°N (Harding et al, 1989).
		Magma transport through the melt generation region of the uppermost mantle (which extends to at least 75 km depth) must, when magma reaches the base of the crust, be focused to horizontal-length scales of only 5-10 km, which is to say into relatively narrow conduits.
	www.ldeo.columbia.edu /users/menke/coax (2555 words)

	magma chamber (Site not responding. Last check: 2007-11-05)
		Magma chambers usually lie at high levels within a volcano, reflecting the gradual accumulation of smaller magma batches that were produced by melting the mantle and/or crust at greater depths.
		It is correct to envision these chambers are forming by expansion of the volcano as the chamber is inflated during accumulation of magma; they do not form by filling an empty cavern beneath a volcano.
		Magma chambers range in size from less than one to a few kilometers in diameter (these tend to be roughly spherical) beneath cinder cones, shield volcanoes, or composite cones, to over 60 km wide (but probably only 1-10 km thick) beneath large pyroclastic calderas.
	www.geology.wisc.edu /~g111/Terms/magma_chamber/magma_chamber.htm (155 words)

	Volcanic Chamber (Site not responding. Last check: 2007-11-05)
		A magma chamber is shallow storage chamber for molten rock 1 to 10 km underground.
		Explosive eruptions are fed by shallow magma chambers, and are mainly characterized by a water-saturated magma, a temporal-increasing eruption-rate and deep seismicity following the later stages of eruption.
		It is found that for a given magma volatile content and conduit geometry, variations in the chamber volume, depth and aspect ratio have a significant impact on the mass erupted and the eruption duration.
	www.volcanolive.com /chamber.html (100 words)

	PETROGENESEN AV LAGDELTE INTRUSJONER
		Magma chambers are large pockets of molten rock that are emplaced, slowly cool, crystallise and differentiate within the crust of the Earth, commonly beneath active central volcanoes.
		Cooling of magma chambers is commonly interrupted by periodic replenishment and the incursions of fresh magma may interact and mix in various ways with the resident melts, depending principally on viscosity and density differences and the momentum of the inflowing melts.
		This is considered to be a consequence of mixing of resident magma saturated with plagioclase, orthopyroxene and ilmenite and inflowing magma with plagioclase and olivine on the liquidus and the curvature of the natural plagioclase-orthopyroxene-ilmenite cotectic (Jensen et al.
	www.uib.no /People/ngebr/NFR-04.htm (3423 words)

	snvolcanics
		Repeated tappings of the magma chamber blanketed the region with air-fall pumice typically several meters thick with a maximum thickness of 12 meters near the vent.
		The roof of the magma chamber ruptured catastrophically at 0.73 Ma ejecting 600 km3 of magma which became to be known as the Bishop Tuff.
		This implies that the magma chamber’s roof was at ~6 km depth when the eruption began and the final ash flows came from ~10 km deep.
	seis.natsci.csulb.edu /rmorris/snvolcan.htm (5535 words)

	Calderas
		As pressure is released by initial eruptions, and the level of the magma chamber falls, the pressure is lowered on the magma causing the underlying layers to degas violently.
		These occur at the summit of the shield complex and are associated with the rise and fall of magma in the magma chamber.
		All calderas are the result of the collapse of a magma chamber, either through the failure of the chamber's ceiling, or through its violent disintegration through an explosion.
	www.mindspring.com /~koz/papers/caldera.html (1512 words)

	Magma chamber - Psychology Central (Site not responding. Last check: 2007-11-05)
		If the magma is not vented to the surface in a volcanic eruption it will slowly cool and crystalize at depth to form an intrusive igneous body such as granite or gabbro.
		Magma chamber is a reservoir of molten rock material beneath the earth's surface.
		A magma chamber is connected to the earth's surface by a vent where magma is extruded onto the surface as lava.
	psychcentral.com /psypsych/Magma_chamber (232 words)

	[No title]
		Mix well to form magma chamber and place at one end of the white sheet of paper to form your magma chamber.
		Also calculate the proportion of magma remaining (f) as a function of the atoms remaining as a fraction of the original number of M&M’s.
		Explain how the percentage of silica in magma increases during crystallization despite the fact that silicate minerals are being removed throughout the crystallization process.
	www.macalester.edu /geology/wirth/MMHandoutIntro.doc (415 words)

	USGS Photo Glossary:
		Magma is molten or partially molten rock beneath the Earth's surface.
		When magma erupts onto the surface, it is called lava.
		Magma typically consists of (1) a liquid portion (often referred to as the melt); (2) a solid portion made of minerals that crystallized directly from the melt; (3) solid rocks incorporated into the magma from along the conduit or reservoir, called xenoliths or inclusions; and (4) dissolved gases.
	volcanoes.usgs.gov /Products/Pglossary/magma.html (111 words)

	More Bad News for Radiometric Dating
		In addition, the magma chamber would be expected to be cooler all around its borders, both at the top and the bottom as well as in the horizontal extremities, and these effects must also be taken into account.
		The solubility of various substances in the magma also could be a function of temperature, and have an influence on the composition of the magma at the top and bottom of the magma chamber.
		Later on the magma is poor in iron, magnesium, and calcium and rich in uranium, thorium, sodium, and potassium.
	www.cs.unc.edu /~plaisted/ce/dating2.html (11376 words)

	Magma Chamber
		When magma is erupted onto the surface in the form of lava, it becomes rock; basalt, andesite, dacite, rhyolite, and other forms of silicate rock.
		As shown in this drawing, magma in the "chamber" evolves over time into chemical compositions which result in different forms of rock, as if the magma were "cooking".
		It is too hot within the chamber itself for rock to crystallize, as shown in the picture, but on subsequent eruptions, lava which pours out of the chamber is composed of different material.
	www.windows.ucar.edu /tour/link=/earth/interior/magma_chamber.html&edu=high (234 words)

	Reference.com/Encyclopedia/Magma
		Magma is a complex high-temperature silicate solution that is ancestral to all igneous rocks.
		Magma exists between 650 and 1200 degrees C. Magma is under high pressure and sometimes emerges through volcanic vents in the form of flowing lava and pyroclastic ejecta.
		Igneous rocks are derived from magma through solidification and related processes or through eruption of the magma at the surface.
	www.reference.com /browse/wiki/Magma (185 words)

	ignimbrites
		The flow of magma occurs as soon as a sufficient pressure gradient is re-established between the chamber and the surface and the flow rate is basically controlled by the bubble growth rate.
		As magma is withdrawn, the amount of magma versus gas in the chamber will change, with a consequent change in the seismic wave generation because of the large acoustic impedance between the magma-gas mixture and the country rock.
		This is interpreted to coincide with the inward collapse of the magma chamber.
	vulcan.fis.uniroma3.it /lavori/ignimbriti/ignimbrites.html (9619 words)

	Crater Lake National Park: Nature Notes (1998)
		The magma chamber is less than four miles from the surface, and it is in the general shape of a lens.
		It is highly improbable that a magma chamber would show two very different types of chemistries unless the compositions were separated from each other into layers within the magma chamber.
		As stated previously, the intermingling of silicic and mafic magma is the most important piece of evidence that the chamber feeding the mountain during the climactic eruption was layered with a lens of mostly gaseous, silicic magmas separated from the dense basaltic material beneath it.
	www.nps.gov /crla/notes/vol29b.htm (2880 words)

	How do volcanos erupt? (Site not responding. Last check: 2007-11-05)
		At Hawaiian volcanoes for example, where the magma is very fluid, a small increase in supply to the magma chamber from deeper within the earth is often sufficient to cause the magma chamber to expand.
		At other volcanoes that are not as active as the Hawaiian examples the magma chamber is not replenished very often because the supply of magma from deeper within the earth is not as great.
		This allows the magma in the chamber to "differentiate", meaning that many crystals form and sink to the bottom of the chamber and at the same time gas bubbles form and float to the top of the chamber.
	volcano.und.nodak.edu /vwdocs/frequent_questions/grp10/question165.html (354 words)

	Physics and chemistry of magma chamber processes - Volcanic and Magmatic Processes Research Group - Trinity College ...
		There, several discrete layers of magma have mutually exchanged phenocrysts which have been redistributed within the chamber with an overall tendency for crystals to be transported from the chamber top towards lower stratigraphic levels of the reservoir.
		Compositional spectrum of end-member magmas involved in ignimbrite "A" eruption on Gran Canaria is reflected in the range of different coloured fiamme (collapsed pumices) set in a fine grained ash matrix.
		This is to establish a record of processes and events during magma storage that correspond to eruption triggers and to constrain mass fluxes in active subduction zone systems.
	www.tcd.ie /Geology/MAIN-PAGE/VAMP/projects/major3.php (1047 words)

	Geologic Applications - InSAR and Land Surface Deformation (Site not responding. Last check: 2007-11-05)
		Prior to an eruption, magma from a deep source migrates upward to a shallow magma storage chamber.
		During the eruption, magma migrates out of the shallow storage chamber and upward to the edifice of the volcano.
		During the eruption, magma migrates from the chamber to the surface of the volcano.
	edcwww.cr.usgs.gov /Geo_Apps/movies.html (399 words)

	Guardian Unlimited \| Life \| Add magma and stand well back
		If the crystal sits around for a long time in the shallow magma chamber then the iron and magnesium begin to diffuse; instead of seeing a sharp boundary between the core and rim, you start to see a smeared out band.
		Scientists at the time recorded the rate of magma output and this data gave Morgan some idea of the rate at which the volcano was being supplied with magma.
		Seismic surveys had shown that the shallow magma chamber under Vesuvius was long and thin, but the volume of the chamber just wasn't clear from these fuzzy images.
	www.guardian.co.uk /life/feature/story/0,13026,1220143,00.html (820 words)

	Evidence for a smaller magma chamber beneath the East Pacific Rise at 9°30' N
		Cross-axis seismic reflection profiles from the East Pacific Rise, however, constrain the width of the axial magma chamber to be < 3–4 km (ref. 3).
		Even this may be an over-estimate, arising from the under-migration of diffracted energy generated at the edges of a smaller magma chamber.
		Reflectivity modelling also suggests that the available data are consistent with a magma chamber comprising only a thin layer of melt.
	www.nature.com /doifinder/10.1038/344650a0 (217 words)

	Re: what makes volcanos erupt
		Magma (molten rock still in the ground) rises as bouyant blobs from source areas in the earth's mantle or lower crust.
		Also, magma is stickier than soda and so the bubble tend to stay trapped in the magma.
		The magma chamber is surrounded by solid rock and cannot expand, so that extra volume must get out of the chamber somehow and it does so by squeezing out the crack and onto the surface.
	www.madsci.org /posts/archives/nov2000/975439775.Es.r.html (588 words)

	MAIN THOLEIITE SHIELD
		A magma chamber migrates upward as the volcano grows, and the magma chambers of Mauna Loa and Kilauea are both 2-3 km below the summits.
		As soon as the magma comes into the magma chamber and stops moving upward, these xenoliths can no longer be supported and they sink to the floor of the chamber.
		Calderas result from collapse and/or subsidence into the magma chamber, thus a caldera is a sign that an active magma chamber is or once was present, and this in turn implies a high supply to the volcano.
	volcano.und.nodak.edu /vwdocs/hawaii_review/life_stages/alkalic/main_shield.html (710 words)

	Volcanoes of the Eastern Sierra Nevada
		Thus, during the eruptive lull between the two episodes, the magma chamber evolved from its period of coalescence to the mature, high-level Long Valley magma chamber (Metz and Mahood, 1985).
		The deeper sections of the magma chamber are represented by the ignimbrite sheets that have higher concentrations of crystals, are pyroxene-bearing, and exhibit gradual increases in Fe-Ti-oxide temperatures up to ~790 degrees Celsius (Bindeman and Valley, 2002).
		As no mafic magma was extruded with the rhyolite of the Bishop Tuff (Bindeman and Valley, 2002), quenched globular basaltic inclusions in these post-caldera rhyolites suggest that mafic magma had been re-introduced into the Long Valley magma system after an absence of 1.8 million years (Bailey, 2004).
	www.indiana.edu /~sierra/papers/2005/smith.html (4077 words)

	Simplified inflation-deflation cycle of magma reservoirs at Hawaiian volcanoes
		A tilt to the northwest recorded at this station is, therefore, a tilt away from the magma chamber and is usually indicative of magma reservoir inflation.
		However, if the same tilt were recorded at a tiltmeter located on the southeast side of the magma chamber, this would be a tilt toward the magma chamber, indicating a deflation of the magma reservoir.
		The summit magma reservoir begins to deflate when magma moves laterally into a rift zone and either erupts or is stored there.
	hvo.wr.usgs.gov /howwork/subsidence/inflate_deflate.html (345 words)

	PLANETARY ENVIRONMENTAL CONTROLS ON MAGMA CHAMBER GROWTH (Site not responding. Last check: 2007-11-05)
		The depth below the surface to which magma can penetrate from the mantle is controlled by the possible presence of a super-lithostatic pressure in the source region and by the variation with depth of both the magma density and the components of lithostatic stress and strength.
		Magmas exsolve juvenile volatiles as a function of pressure, and those erupted at the surface produce vesicular lava flows or poorly compacted pyroclastic layers.
		This places the depth at which rising magmas are neutrally buoyant closer to the surface and influences the nature (sheet-like or dike-like) of the intrusions.
	gsa.confex.com /gsa/2005AM/finalprogram/abstract_92352.htm (476 words)

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