Featured Research

from universities, journals, and other organizations

Scientists describe a 'new' type of volcanic eruption

Date:
January 21, 2013
Source:
National Oceanography Centre
Summary:
Scientists based in the UK and New Zealand have described a “new” type of volcanic eruption. Volcanic eruptions are commonly categorized as either explosive or effusive. But now, researchers have uncovered a previously undocumented type of eruption in underwater volcanoes – by looking at tiny original bubble spaces trapped in volcanic rock.

Macauley volcano.
Credit: Courtesy of National Oceanography Centre & National Institute of Water and Atmospheric Research

Scientists based in the UK and New Zealand have described a "new" type of volcanic eruption.

Volcanic eruptions are commonly categorised as either explosive or effusive. But now, in research published this month in Nature Geoscience, researchers at Victoria University, Wellington and the National Oceanography Centre in Southampton have uncovered a previously undocumented type of eruption in underwater volcanoes -- by looking at tiny original bubble spaces trapped in volcanic rock.

Inside volcanoes, gases are dissolved in the molten magma as a function of the very high pressures and chemistry of the magma. In the same way that gases dissolved in carbonated drinks bubble up when you take the lid off, when magma is erupted as lava, the pressure is relieved and the gases exsolve to form small gas bubbles or so-called "vesicles." In explosive eruptions these vesicles expand so quickly they fragment the magma, violently ejecting lava, which cools and degasses to form solidified pumice that can be sufficiently light to float on water.

In air pumice is obviously associated with violent, explosive eruptions. Consequently underwater volcanoes flanked by highly vesicular pumice have, to date, also been interpreted as having erupted explosively.

But the results of this study indicate that there is a third eruptive style unique to underwater volcanoes, which is neither effusive nor explosive.

"By documenting the shape and density of bubbles in pumices generated by an underwater caldera volcano in the southwest Pacific Ocean -- the Macauley volcano -- we found large differences in the number and shape of "bubbles" in the same pebble-sized samples, different to anything previously documented," said Professor Ian Wright of the National Oceanography Centre, who co-authored the paper.

"This range of bubble densities distinct in these pumice samples indicates that the lava erupting from the caldera was neither vigorous enough for an explosive eruption, nor gentle enough for an effusive flow."

The study proposes that rather than exploding in the neck of the volcano, the formation and expansion of bubbles in the magma created a buoyant foam, which rose to the seafloor and then buoyantly detached from the volcano as molten pumice balloons but with chilled margins. During its ascent to the sea surface, the vesicles within the molten interior would have continued to expand as the pressure -- this time from the weight of the seawater -- reduced.

"These processes explain the unique bubble structure seen in the samples analysed, which could have only occurred with an intermediate eruption style and in an underwater setting," said Professor Wright.

"We conclude that the presence of widespread deposits of pumice on underwater volcanoes does not necessarily indicate large-scale explosive volcanism."

The authors proposed that this style of eruption be named Tangaroan, the Maori god of the sea, and name of the research vessel used to collect the samples.

The study was led by Melissa Rotella, Professor Colin Wilson and Simon Barker from the School of Geography, Environment and Earth Sciences at the Victoria University of Wellington, New Zealand.


Story Source:

The above story is based on materials provided by National Oceanography Centre. Note: Materials may be edited for content and length.


Journal Reference:

  1. Melissa D. Rotella, Colin J. N. Wilson, Simon J. Barker, Ian C. Wright. Highly vesicular pumice generated by buoyant detachment of magma in subaqueous volcanism. Nature Geoscience, 2013; DOI: 10.1038/NGEO1709

Cite This Page:

National Oceanography Centre. "Scientists describe a 'new' type of volcanic eruption." ScienceDaily. ScienceDaily, 21 January 2013. <www.sciencedaily.com/releases/2013/01/130121083215.htm>.
National Oceanography Centre. (2013, January 21). Scientists describe a 'new' type of volcanic eruption. ScienceDaily. Retrieved August 21, 2014 from www.sciencedaily.com/releases/2013/01/130121083215.htm
National Oceanography Centre. "Scientists describe a 'new' type of volcanic eruption." ScienceDaily. www.sciencedaily.com/releases/2013/01/130121083215.htm (accessed August 21, 2014).

Share This




More Earth & Climate News

Thursday, August 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

California Drought Stings Honeybees, Beekeepers

California Drought Stings Honeybees, Beekeepers

AP (Aug. 21, 2014) — California's record drought is hurting honey supplies and raising prices for consumers. The lack of rainfall means fewer crops and wildflowers that provide the nectar bees need to make honey. (Aug. 21) Video provided by AP
Powered by NewsLook.com
Thousands Of Species Found In Lake Under Antarctic Ice

Thousands Of Species Found In Lake Under Antarctic Ice

Newsy (Aug. 20, 2014) — A U.S. team found nearly 4,000 species in a subglacial lake that hasn't seen sunlight in millennia, showing life can thrive even under the ice. Video provided by Newsy
Powered by NewsLook.com
Unsustainable Elephant Poaching Killed 100K In 3 Years

Unsustainable Elephant Poaching Killed 100K In 3 Years

Newsy (Aug. 20, 2014) — Poachers have killed 100,000 elephants between 2010 and 2012, as the booming ivory trade takes its toll on the animals in Africa. Video provided by Newsy
Powered by NewsLook.com
Charter Schools Alter Post-Katrina Landscape

Charter Schools Alter Post-Katrina Landscape

AP (Aug. 20, 2014) — Nine years after Hurricane Katrina, charter schools are the new reality of public education in New Orleans. The state of Louisiana took over most of the city's public schools after the killer storm in 2005. (Aug. 20) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins