Earth Science News  





. Decompression-Driven Crystallization Warms Pathway for Volcanic Eruptions

"This work is now being used to gauge the direction of the volcanic activity currently happening at Mount St. Helens and could be applied to any active volcano for which monitoring and petrological records are available, said Jon Blundy, professor of earth sciences at the University of Bristol (United Kingdom), in a news release.
by Staff Writers
Eugene OR (SPX) Sep 08, 2006
The reason may be counter-intuitive, but the more magma crystallizes, the hotter it gets and the more likely a volcano will erupt, according to a team of scientists that includes a University of Oregon geologist. The knowledge likely will aid monitoring of conditions at Mount St. Helens and other volcanic hot spots around the world.

Reporting in the Sept. 7 issue of the journal Nature, the researchers show that rapid crystallization of magma within one to two kilometers of the surface (about one-half to one mile) causes magma to heat up to as much as 100 degrees Celsius (212 degrees Fahrenheit).

"While this sort of heating has been expected in theory, we are the first to show that we can measure it, said Katharine Cashman, a professor of geologic sciences at the University of Oregon. "These results have important consequences for models of magma ascent beneath volcanoes, as increasing the melt temperatures causes the melt viscosity to decrease so that it can flow more easily, like heating up a jar of honey to allow the honey to flow out of the jar.

Explosive volcanic eruptions are fueled by the escape of volcanic gases from magma stored in underground reservoirs and pipes several kilometers below the surface. Predicting such eruptions requires a real-time knowledge of just where the magma is at any one time and what it is doing.

"This work is now being used to gauge the direction of the volcanic activity currently happening at Mount St. Helens and could be applied to any active volcano for which monitoring and petrological records are available, said Jon Blundy, professor of earth sciences at the University of Bristol (United Kingdom), in a news release.

Cashman and Blundy have now collaborated since 1998, when Blundy took a sabbatical at the University of Oregon, on four published studies on Mount St. Helens, located 53 miles northeast of Portland, Ore. Cashman has studied the volcano and similar ones elsewhere for more than a decade.

The latest study was a follow-up to one Blundy and Cashman published in Geology last year (October 2005), in which they used small pockets of melt that get trapped in crystals as they expand to demonstrate that the crystals grow by decompression as magma rises toward the surface. That paper also showed that these crystals grow rapidly, in months rather than years. The new study refined their conclusions in Geology by using experimental calibrations to show the rapid heating as magma nears the surface.

"This may sound counter-intuitive, but think about the need to add heat to something to melt it, Cashman said.

In this follow-up study to last year's report, the researchers were able to reconstruct changes in pressure, temperature and crystallization that occur in magma before an eruption. They showed that as pressure decreases, crystallinity increases; the more magma crystallizes, the hotter it gets.

The finding that a drop in pressure rather than a loss of heat to surrounding rocks, as previously thought, means that there are more possibilities for eruption dynamics, the researchers concluded.

If ascending magma is able to heat itself up simply by crystallizing, they report, it may provide an important trigger for eruption without the need to invoke an extraneous heat source such as a shot of hotter magma from deep below the surface. The new findings also suggest the possibility that volcanic crystals grow in response to decompression by heating on an unexpectedly short timescale of several years, a period during which volcanoes can be more effectively monitored.

Related Links
University of Oregon
A world of storm and tempest

Philippines Volcano Eruption May Have Run Its Course
Manila (AFP) Sep 07, 2006
The Mayon volcano's eight-week eruption is nearing its end, giving fresh hope to tens of thousands of people displaced by its lava flows, Philippine authorities said Thursday. More than 40,000 people were ordered off the lower slopes of the country's most active and deadly volcano when scientists warned of an imminent eruption following weeks of quiet lava flows that incinerated farmlands.

.
Get Our Free Newsletters Via Email
  



  • Trauma Expert Crusades For Changes In Disaster Preparedness And Recovery
  • China To Build Earthquake Warning System At Three Gorges Reservoir Area
  • Interview: Katrina Lessons Learned
  • Katrina Response A 'Systemic Failure': Former US Emergency Response Chief

  • Climate Change Rocked Cradles Of Civilization
  • Precision Climate Modeling Is Forecast
  • Siberian Lakes Burp Time-Bomb Greenhouse Gas
  • Greenhouse Gas Bubbling From Melting Permafrost Feeds Climate Warming

  • DMC International Imaging Wins 2nd Year Contract To Monitor Amazonian Rainforest
  • What Is It Like To Be On A NASA Hurricane Mission
  • Renewed Volcanic Activity At The Phlegrean Fields Tracked By Envisat
  • China To Launch 1st Environment Monitoring Satellite

  • Moscow Mayor Says Winter Energy Deficit Could Reach 20 Percent
  • Fresh Declines For Oil Prices As Iran Fears Recede
  • Schwarzenegger Ready To Sign Bill Limiting Greenhouse Gas Emissions
  • Protesters Aim To Shut Down British Power Station

  • Satellites Track Migratory Birds In Fight Against Avian Influenza
  • Cancer Surge Overwhelming AIDS-Crisis Botswana
  • Africa Braces For New, Deadly, TB Strains
  • Viruses Can Jump Between Primates And Humans

  • Genetic Surprise Confirms Neglected 70-Year-Old Evolutionary Theory
  • Analysis: Animal-Rights Groups Up The Ante
  • A Cognitive Strategy Shared By Human Infants And Our Great-Ape Kin
  • Embosymbiont Offers Clues To How Plants Came To Be

  • Environmental Pollution Costs China 64 Billion Dollars In 2004
  • Analysis: No Room For Shangri-La In China
  • Over 2000 Feared To Have Lead Poisoning In China
  • Ivory Coast Government Resigns Over Pollution Scandal

  • How Did Our Ancestors' Minds Really Work
  • Ancient Rock Art In Australia Threatened By Major Gas Project
  • Well Educated More Interested In Designing Babies
  • Snakes Credited For Our Keen Vision

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement