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Blobrana


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RE: Volcanoes
 
 

Impact of magma input rate on magma chamber growth - granite intrusion or volcanic eruption?

A computational approach which links processes deep below a volcano to potential eruptions is described by researchers at the University of Bristol in a paper published today in the Journal of Geophysical Research. The research could ultimately help scientists to understand magma chamber processes and volcanic eruption timing.
Violent volcanic eruptions can lead to collapse of the solid lid above the drained magma reservoir and create a depression called a caldera. Such caldera-forming eruptions are among the most devastating natural processes on Earth, threatening not only nearby settlements but also impacting upon the global climate. 
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Blobrana


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Swelling volcanoes could help predict eruptions in Alaska, elsewhere

A new study of Indonesian volcanoes conducted by two University of Miami researchers could hold vital clues to the future of predicting explosive eruptions from volcanic peaks around the globe.
Using data obtained from a satellite-based system known as Interferometric Sythetic Aperture Radar (InSAR), PHd student Estelle Chaussard and her advisor Falk Amelung were able to discern tiny movements in the earth's surface near 79 volcanoes in the highly-volcanic west Sunda arc in Indonesia. They observed "inflation," or a swelling of the earth at six volcanoes using data obtained between 2006 and 2009. In three of those six instances, the volcanoes erupted after observing the inflation.
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Blobrana


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What is it like to be a volcanologist?

Volcanologists are among science's most adventurous researchers, travelling to some of the planet's more remote places to try to better understand one of nature's most powerful and destructive forces - the volcano.
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Blobrana


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 Autopsy of a eruption: Linking crystal growth to volcano seismicity

A forensic approach that links changes deep below a volcano to signals at the surface is described by scientists from the University of Bristol in a paper published today in Science. The research could ultimately help to predict future volcanic eruptions with greater accuracy.
Using forensic-style chemical analysis, Dr Kate Saunders and colleagues directly linked seismic observations of the deadly 1980 Mount St. Helens eruption to crystal growth within the magma chamber, the large underground pool of liquid rock beneath the volcano.
Dr Saunders and colleagues studied zoned crystals, which grow concentrically like tree rings within the magma body. Individual zones have subtly different chemical compositions, reflecting the changes in physical conditions within the magma chamber and thus giving an indication of volcanic processes and the timescales over which they occur.
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Blobrana


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  Volcanic plumbing exposed
 
Two new studies into the "plumbing systems" that lie under volcanoes could bring scientists closer to predicting large eruptions.
International teams of researchers, led by the University of Leeds, studied the location and behaviour of magma chambers on the Earth's mid-ocean ridge system - a vast chain of volcanoes along which the Earth forms new crust.
They worked in Afar (Ethiopia) and Iceland - the only places where mid-ocean ridges appear above sea level. Volcanic ridges (or "spreading centres") occur when tectonic plates "rift" or pull apart. Magma (hot molten rock) injects itself into weaknesses in the brittle upper crust, erupting as lava and forming new crust upon cooling.
Magma chambers work like plumbing systems, channelling pressurised magma through networks of underground "pipes".
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Blobrana


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For Volcanologists Worldwide, a New Digital Home for All Things Volcano

Volcanologists now have their own online network: VHub.org, which promotes collaboration among volcano researchers and community partners by providing a place to share everything from eruption data to ash cloud simulations.
The website, created by the University at Buffalo's volcanology group, represents an innovative approach to facilitating partnerships around the world. Funding for the project comes from the National Science Foundation (NSF).
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Blobrana


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How to watch world volcanoes on the web

During the past several weeks, many volcanoes have been active around the world. While we focus on our home volcano, it can be very interesting to check in with these other eruptions via the internet. The volcanoes getting the most attention now are El Hierro in the Canary Islands northwest of mainland Africa, Mount Etna on the Italian Island of Sicily, and Nyamuragira volcano in the Congo. You can keep up with world volcanism here
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Blobrana


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Super-eruptions
 
 

Scientists find possible trigger for volcanic super-eruptions

The "super-eruption" of a major volcanic system occurs about every 100,000 years and is considered one of the most catastrophic natural events on Earth, yet scientists have long been unsure about what triggers these violent explosions.
However, a new model presented this week by researchers at Oregon State University points to a combination of temperature influence and the geometrical configuration of the magma chamber as a potential cause for these super-eruptions.
Results of the research, which was funded by the National Science Foundation, were presented at the annual meeting of the Geological Society of America in Minneapolis, Minn.
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Blobrana


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RE: Volcanoes
 
 

Three Active Volcanoes Spotted on Satellite Imagery from NASA

NASA keeps a watchful eye on volcanic activity around the world with many satellites. NASA has just released satellite images showing activity this week from volcanoes in the countries of Eritrea, Chile and Indonesia.
NASA's Terra satellite and the GOES-11 satellite captured ash plumes or heat coming from the Nabro volcano, the Puyehue-Cordón volcano, and the Soputan volcano, respectively, over the past week. There are a number of other volcanoes showing activity around the world, but thanks to good visibility these three volcanoes were more easily seen from space this week.
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Blobrana


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Title: A rapid mechanism to remobilise and homogenise highly crystalline magma bodies
Authors: Alain Burgisser, George W. Bergantz,

The largest products of magmatic activity on Earth, the great bodies of granite and their corresponding large eruptions, have a dual nature: homogeneity at the large scale and spatial and temporal heterogeneity at the small scale. This duality calls for a mechanism that selectively removes the large-scale heterogeneities associated with the incremental assembly of these magmatic systems and yet occurs rapidly despite crystal-rich, viscous conditions seemingly resistant to mixing. Here we show that a simple dynamic template can unify a wide range of apparently contradictory observations from both large plutonic bodies and volcanic systems by a mechanism of rapid remobilisation (unzipping) of highly viscous crystal-rich mushes. We demonstrate that this remobilisation can lead to rapid overturn and produce the observed juxtaposition of magmatic materials with very disparate ages and complex chemical zoning. What distinguishes our model is the recognition that the process has two stages. Initially, a stiff mushy magma is reheated from below, producing a reduction in crystallinity that leads to the growth of a subjacent buoyant mobile layer. When the thickening mobile layer becomes sufficiently buoyant, it penetrates the overlying viscous mushy magma. This second stage rapidly exports homogenized material from the lower mobile layer to the top of the system, and leads to partial overturn within the viscous mush itself as an additional mechanism of mixing. Model outputs illustrate that unzipping can rapidly produce large amounts of mobile magma available for eruption. The agreement between calculated and observed unzipping rates for historical eruptions at Pinatubo and at Montserrat demonstrates the general applicability of the model. This mechanism furthers our understanding of both the formation of periodically homogenised plutons (crust building) and of ignimbrites by large eruptions.

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