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Blobrana


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RE: Volcanoes
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Climate researchers have shown that big volcanic eruptions over the past 450 years have temporarily cooled weather in the tropics - but suggest that such effects may have been masked in the 20th century by rising global temperatures. Their paper, which shows that higher latitudes can be even more sensitive to volcanism, appears in the current issue of Nature Geoscience.
Scientists already agree that large eruptions have lowered temperatures at higher latitudes in recent centuries, because volcanic particles reflect sunlight back into space. For instance, 1816, the year following the massive Tambora eruption in Indonesia, became known as "The Year Without a Summer," after low temperatures caused crop failures in northern Europe and eastern North America. More extensive evidence comes in part from tree rings, which tend to grow thinner in years when temperatures go down.
This is one of the first such studies to show how the tropics have responded, said lead author Rosanne D'Arrigo, a scientist at the Tree Ring Lab at Columbia University's Lamont-Doherty Earth Observatory

Source The Earth Institute at Columbia University

Title: The impact of volcanic forcing on tropical temperatures during the past four centuries
Authors: Rosanne D'Arrigo, Rob Wilson & Alexander Tudhope

Palaeoclimate records have demonstrated links between high-latitude climate changes and tropical as well as high-latitude volcanic activity. However, little is known about the impact of high-or low-latitude volcanic eruptions on tropical climate, particularly for the period preceding the instrumental record. Here we use annually resolved temperature-related records from corals, tree rings and ice cores to investigate the relationship between volcanism and low-latitude climate. Over the past 450 years, we find an association between low-latitude volcanic events and lower sea surface temperatures in the tropical oceans. The longest sustained cold period in recent centuries occurred in the early nineteenth century, following the eruption of Tambora and a second, unidentified but presumably tropical, volcano. We therefore conclude that the tropical ocean-atmosphere system has been sensitive to changes in radiative forcing caused by tropical volcanism over the past several centuries.

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Blobrana


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Superplumes
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Two giant plumes of hot rock deep within the earth are linked to the plate motions that shape the continents, researchers have found.
The two superplumes, one beneath Hawaii and the other beneath Africa, have likely existed for at least 200 million years, explained Wendy Panero, assistant professor of earth sciences at Ohio State University.
The giant plumes -- or "superpiles" as Panero calls them -- rise from the bottom of Earth's mantle, just above our planet's core. Each is larger than the continental United States. And each is surrounded by a wall of plates from Earth's crust that have sunk into the mantle.
She and her colleagues reported their findings at the American Geophysical Union meeting in San Francisco.
 
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Blobrana


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RE: Volcanoes
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A Scots scientist who invented a new way to help predict when volcanoes will erupt has received a major award.
Dr Andrew McGonigle, from Edinburgh, uses a remote controlled helicopter which he flies over active volcanoes to gather his data.
He has been named a Laureate in the 2008 Rolex Awards for Enterprise, a prize which brings with it the funding to develop his idea further.

"What we are trying to do is develop a completely remote way of measuring carbon dioxide emissions from volcanoes. Carbon dioxide as a gas is very important with volcanology because it is released from rising batches of magma relatively early in the ascent process" - Dr Andrew McGonigle.

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Blobrana


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Deep magma matters in volcanic eruption cycle
Although the Soufriere Hills volcano on Montserrat exhibits cycles of eruption and quiet, an international team of researchers found that magma is continuously supplied from deep in the crust but that a valve acts below a shallower magma chamber, releasing lava to the surface periodically.

"Continuous records of surface deformation are available for only a few volcanoes.  The Soufriere Hills volcano has been erupting since 1995 and provides a peek into the processes occurring deep beneath this stratovolcano" - Derek Elsworth, professor of energy and geo-environmental engineering, Penn State.

Stratovolcanoes are one of the most common forms of volcano on Earth. They are cone-shaped with steep sides created by episodic eruptions of magma that flow down from the cone a short way and create layer upon layer of volcanic material.

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Blobrana


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The plumes of hot magma that fuel the volcanism of "hotspots" like Hawaii and Iceland have long been thought to be efficient conduits of Earth's fiery contents. Yet it seems they can be rather lacklustre on their way to the surface.
We traditionally picture the plumes of hot magma that rise through the mantle as mushroom-shaped with a thin stalk feeding a bulbous head, or hotspot, beneath the crust. However, seismic imaging in Iceland reveals a patchy structure without a stalk, leading some researchers to suggest there are no plumes at all.

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Blobrana


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A research team led by the Woods Hole Oceanographic Institution (WHOI) has uncovered evidence of explosive volcanic eruptions deep beneath the ice-covered surface of the Arctic Ocean. Such violent eruptions of splintered, fragmented rockknown as pyroclastic depositswere not thought possible at great ocean depths because of the intense weight and pressure of water and because of the composition of seafloor magma and rock.

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Blobrana


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Volcanic trace metals
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Scientists from the Universities of Oxford and Cambridge have discovered how volatile metals from volcanoes end up in polar ice cores.

"It has always been a mystery how trace metals, like mercury, with a volcanic signature find their way into polar ice in regions without nearby evidence of volcanic activity" - Dr David Pyle, Department of Earth Sciences, Oxford University.

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Blobrana


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Several huge active submarine volcanoes, spreading ridges and rift zones have been discovered northeast of Fiji by a team of Australian and American scientists aboard the Marine National Facility Research Vessel, Southern Surveyor.
On the hunt for subsea volcanic and hot-spring activity, the team of geologists located the volcanoes while mapping previously uncharted areas. Using high-tech multi-beam sonar mapping equipment, digital images of the seafloor revealed the formerly unknown features.
The summits of two of the volcanoes, named 'Dugong', and 'Lobster', are dominated by large calderas at depths of 1100 and 1500 metres.

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Blobrana


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Researchers from McGill University and the University of British Columbia (UBC) have simulated in the lab the process that can turn ordinary volcanic eruptions into so-called supervolcanoes, with potentially devastating worldwide impact.
The study was conducted by Dr. Ben Kennedy and and Dr. Mark Jellinek of UBCs Department of Earth and Ocean Sciences, and Dr. John Stix, chair of McGill Universitys Department of Earth and Planetary Sciences. Their results were published May 25 in the journal Nature Geoscience.

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Blobrana


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Underwater volcanoes
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Scientists from Durham University will use robots to explore the depths of the Atlantic Ocean to study the growth of underwater volcanoes that build the Earths crust.
The Durham experts will lead an international team of 12 scientists aboard Britains Royal Research Ship (RRS) James Cook which will set sail from Ponta Delgada, San Miguel, in the Azores, on Friday, May 23.

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