mick silver
18th December 2014, 01:42 PM
Violent Volcanic Blasts Ripped Through Antarctic Ice Sheet Twicehttp://l.yimg.com/a/i/us/nws/p/livesci_logo_73.jpg (http://www.livescience.com/) By Becky Oskin 9 hours ago
http://l.yimg.com/bt/api/res/1.2/j5_EvCbgvAA0qZWsUVF8Ww--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTM3NztweG9mZj01MDtweW 9mZj0wO3E9NzU7dz02NzA-/http://media.zenfs.com/en_US/News/LiveScience.com/antarctic-ice-core.jpeg1418838234 (http://news.yahoo.com/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-115608903.html#)
. View gallery
http://l1.yimg.com/bt/api/res/1.2/T9eT7o9SaJeDevjog.KKdg--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTgzLjI1O3B5b2ZmPTE1O3 E9NzU7dz0xNDg-/http://media.zenfs.com/en_US/News/LiveScience.com/Phreatomagmatic-tephra.jpeg1418838724 (http://news.yahoo.com/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-115608903.html#)
.
http://l.yimg.com/bt/api/res/1.2/Y_VDzLvyZQMff5BJzcxyZg--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTgzLjI1O3B5b2ZmPTE1O3 E9NzU7dz0xNDg-/http://media.zenfs.com/en_US/News/LiveScience.com/Subglacial-volcanoes.jpeg1418838638 (http://news.yahoo.com/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-115608903.html#)
.
SAN FRANCISCO — Volcanoes punched through a remote part of the West Antarctic Ice Sheet twice in the last 50,000 years, according to research presented Monday (Dec. 15) here at the annual meeting of the American Geophysical Union.
Related Stories
Warmer Water Speeds Melting of Antarctica Glaciers, Study Says (http://online.wsj.com/articles/warmer-water-speeds-melting-of-antarctica-glaciers-study-says-1417719661?ru=yahoo?mod=yahoo_itp) The Wall Street Journal
Newscast: Coca-Cola puts its polar bears on ice (http://www.marketwatch.com/News/Story/Story.aspx?guid=BDD2E29C-3A16-40CE-B4FA-663673CDFFDD&siteid=yhoof2) MarketWatch
Vulnerable Valleys Found Among Antarctica's Ice-Covered Volcanoes (http://news.yahoo.com/vulnerable-valleys-found-among-antarcticas-ice-covered-volcanoes-230522821.html) LiveScience.com
10 Things No One Tells You About Spray Tanning (https://beap.gemini.yahoo.com/mbclk?bv=1.0.0&es=tYg77BgGIS.XstI5iMp13eOkqElFbyFCwRLEW9OYVc3jIQQ U_AAufx25jF4I.h33YJ_rbI28Jv7Nl2HdhLqUMfaA3AwviTZY_ UbpLqzyIr87JuOhAE81zdjNlZ3t5bCImHnUkg0P2_T1.pcqMoC _n9tnAwkI_hZQxFEvuHORSjLb5_xYTUe3bbueNo7rFL3C3gjs7 wBGIyw0kO6K.JIviRr.VMv9Cgx4bgBpzG_wbgGZnfSIs22ch5K BiSgVcRHwT9YIF.tp9xnA7FqpsKMBEwffeDDUwMngqVAulEZJB 9D4BiMwE2G7B266xaaJ0zHC_RIAUU5M8HJxieWx_CAb3KDVdBN 049LQmXfnGeRMXY43DLe4Q9f0BgPGsYMA1xyifMqcHyE1ubRZc lIf89ZzNJS.xm_idLMkjaeUx74wihMyGj.nMjTM.8Gm0z5l7am VX52d1xMGnB5iqR5mNmT1azPZ.A3CbfThBnQ4KM2cm4lWVfPq3 oiBWXo6ja66pWPpZy5Iohi5_PHIzPCnaIZGB__7rzbNSwhC2Nq 8UZbEotasrN6nEri242p.93oqqryFwB.TUig3asLzNw--%26lp=) Minq.com (http://share.minq.com/click.php?sou=ysa&page=www.minq.com/beauty/3586/10-things-no-one-tells-you-about-spray-tanning&cont=6883586y) Sponsored (https://help.yahoo.com/kb/SLN22774.html?impressions=true) (https://info.yahoo.com/privacy/us/yahoo/relevantads.html)
Distinctive layers of brown ash in a deep ice core are evidence of violent volcanic explosions (http://www.livescience.com/30507-volcanoes-biggest-history.html) that occurred about 22,470 and 45,381 years ago, near the West Antarctic divide. Their source, however, is a mystery.
The closest active volcanoes that rise above the ice are more than 185 miles (300 kilometers) away, said study leader Nels Iverson, a volcanologist and graduate student at the New Mexico Institute of Mining and Technology in Socorro. Powerful eruptions from these peaks (http://www.livescience.com/43990-antarctica-ice-age-refuges-volcanoes.html) have dusted the West Antarctica divide with ash, leaving glassy shards embedded in younger layers of the ice core. However, the ash particles described here Monday are too blocky and coarse to travel long distances, even on Antarctica's fierce winds. The ash is also chemically different from eruptions at the distant volcanoes. And to draw the circle in tighter, neither ash layer appears in an ice core drilled about 60 miles (100 km) to the southeast. [Fire and Ice: Images of Volcano-Ice Encounters (http://www.livescience.com/43902-volcano-ice-eruptions-photos.html)]
"It had to be from somewhere close," Iverson told Live Science. "Ash particles that travel far are shaped like little parachutes. These are like your fists trying to float on air."
Iverson said the rough, glassy shards embedded in the ice are typical of phreatomagmatic eruptions, the spectacular outbursts that occur when lava meets water. This kind of eruption killed 57 people at Japan's Mount Ontake volcano (http://www.livescience.com/48058-why-ontake-erupted-no-warning.html) in September, when water was superheated to steam. Similarly, when lava emerges under glaciers or ice caps, the molten rock melts ice into water and explodes, shattering lava into microscopic bits and flinging ash into the air.
Depending on the ice thickness and eruption size, it's possible for volcanic eruptions to have penetrated the West Antarctic Ice Sheet, said volcanologist Ben Edwards of Dickinson College in Pennsylvania, who was not involved in the study.
View gallery
http://l.yimg.com/bt/api/res/1.2/vtP9LENHUVVqLbAuJZWxcw--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTM5NDtxPTc1O3c9MzAw/http://media.zenfs.com/en_US/News/LiveScience.com/Phreatomagmatic-tephra.jpeg1418838724
(http://news.yahoo.com/photos/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-photo-115608541.html)Blocky ash particles indicate a lava-ice eruption.
Magmas such as the basanite (an igneous rock) from the 45,000-year-old ash layer can melt three to six times their own mass in ice, he said. "The key thing is ice thickness," Edwards said. "Really thick ice makes it more difficult for the magma to explode."
Iverson suspects the volcanic source is buried close to the divide, where the ice sheet is more than 10,000 feet (3,050 meters) thick. There are three volcanoes entombed in ice within about 125 miles (200 km), and even more could be present.
Earthquakes suggest magma still churns beneath a previously unknown subglacial volcano in West Antarctica's Executive Committee Range, which was uncloaked when shaking started in 2010. Gravity and magnetic anomalies hint at nine subglacial volcanoes (http://www.livescience.com/41262-west-antarctica-new-volcano-discovered.html) near the West Antarctic divide, John Behrendt, a geologist at the University of Colorado, Boulder reported today (Dec. 17) at the meeting. Behrendt was not involved in the ice core study.
If a volcano erupts under the ice sheet, it could melt out millions of gallons of water, possibly destabilizing major glaciers. However, scientists don't yet agree on the potential effects of a subglacial eruption.
"We're trying to understand the implications for the stability of the ice sheet," Iverson said.
The West Antarctic Ice Sheet grew up and around an abundance of active volcanoes. For instance, the coastal volcanoes Mount Berlin, Mount Takahe and Mount Siple have erupted some 20 times in the past 571,000 years, according to ash layers in ice cores. Geothermal heating (http://www.livescience.com/46194-volcanoes-melt-antarctic-glaciers.html) has cooked the bottom of the ice sheet in the vicinity of some ice-covered volcanoes, according to recent studies. For instance, at the West Antarctic divide drilling site, researchers recovered about 70,000 years of ice, not 100,000 years as was expected, because the bedrock was hotter than they had assumed.
Follow Becky Oskin @beckyoskin (https://twitter.com/beckyoskin). Follow Live Science @livescience (https://twitter.com/LiveScience), Facebook (http://www.facebook.com/#!/livescience) & Google+ (https://plus.google.com/101164570444913213957/posts). Originally published on Live Science (http://www.livescience.com/49167-antarctica-volcanoes-erupted-through-ice.html).
The World's Five Most Active Volcanoes (http://www.livescience.com/29790-worlds-five-most-active-volcanoes.html)
Album: Stunning Photos of Antarctic Ice (http://www.livescience.com/11259-ice-antarctic.html)
50 Amazing Facts About Antarctica (http://www.livescience.com/43881-amazing-antarctica-facts.html)
Copyright 2014 LiveScience (http://www.livescience.com/), a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Nature & Environment
Natural Phenomena
West Antarctic Ice Sheet
Click to view comments
View Comments (132)
http://l.yimg.com/bt/api/res/1.2/j5_EvCbgvAA0qZWsUVF8Ww--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTM3NztweG9mZj01MDtweW 9mZj0wO3E9NzU7dz02NzA-/http://media.zenfs.com/en_US/News/LiveScience.com/antarctic-ice-core.jpeg1418838234 (http://news.yahoo.com/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-115608903.html#)
. View gallery
http://l1.yimg.com/bt/api/res/1.2/T9eT7o9SaJeDevjog.KKdg--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTgzLjI1O3B5b2ZmPTE1O3 E9NzU7dz0xNDg-/http://media.zenfs.com/en_US/News/LiveScience.com/Phreatomagmatic-tephra.jpeg1418838724 (http://news.yahoo.com/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-115608903.html#)
.
http://l.yimg.com/bt/api/res/1.2/Y_VDzLvyZQMff5BJzcxyZg--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTgzLjI1O3B5b2ZmPTE1O3 E9NzU7dz0xNDg-/http://media.zenfs.com/en_US/News/LiveScience.com/Subglacial-volcanoes.jpeg1418838638 (http://news.yahoo.com/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-115608903.html#)
.
SAN FRANCISCO — Volcanoes punched through a remote part of the West Antarctic Ice Sheet twice in the last 50,000 years, according to research presented Monday (Dec. 15) here at the annual meeting of the American Geophysical Union.
Related Stories
Warmer Water Speeds Melting of Antarctica Glaciers, Study Says (http://online.wsj.com/articles/warmer-water-speeds-melting-of-antarctica-glaciers-study-says-1417719661?ru=yahoo?mod=yahoo_itp) The Wall Street Journal
Newscast: Coca-Cola puts its polar bears on ice (http://www.marketwatch.com/News/Story/Story.aspx?guid=BDD2E29C-3A16-40CE-B4FA-663673CDFFDD&siteid=yhoof2) MarketWatch
Vulnerable Valleys Found Among Antarctica's Ice-Covered Volcanoes (http://news.yahoo.com/vulnerable-valleys-found-among-antarcticas-ice-covered-volcanoes-230522821.html) LiveScience.com
10 Things No One Tells You About Spray Tanning (https://beap.gemini.yahoo.com/mbclk?bv=1.0.0&es=tYg77BgGIS.XstI5iMp13eOkqElFbyFCwRLEW9OYVc3jIQQ U_AAufx25jF4I.h33YJ_rbI28Jv7Nl2HdhLqUMfaA3AwviTZY_ UbpLqzyIr87JuOhAE81zdjNlZ3t5bCImHnUkg0P2_T1.pcqMoC _n9tnAwkI_hZQxFEvuHORSjLb5_xYTUe3bbueNo7rFL3C3gjs7 wBGIyw0kO6K.JIviRr.VMv9Cgx4bgBpzG_wbgGZnfSIs22ch5K BiSgVcRHwT9YIF.tp9xnA7FqpsKMBEwffeDDUwMngqVAulEZJB 9D4BiMwE2G7B266xaaJ0zHC_RIAUU5M8HJxieWx_CAb3KDVdBN 049LQmXfnGeRMXY43DLe4Q9f0BgPGsYMA1xyifMqcHyE1ubRZc lIf89ZzNJS.xm_idLMkjaeUx74wihMyGj.nMjTM.8Gm0z5l7am VX52d1xMGnB5iqR5mNmT1azPZ.A3CbfThBnQ4KM2cm4lWVfPq3 oiBWXo6ja66pWPpZy5Iohi5_PHIzPCnaIZGB__7rzbNSwhC2Nq 8UZbEotasrN6nEri242p.93oqqryFwB.TUig3asLzNw--%26lp=) Minq.com (http://share.minq.com/click.php?sou=ysa&page=www.minq.com/beauty/3586/10-things-no-one-tells-you-about-spray-tanning&cont=6883586y) Sponsored (https://help.yahoo.com/kb/SLN22774.html?impressions=true) (https://info.yahoo.com/privacy/us/yahoo/relevantads.html)
Distinctive layers of brown ash in a deep ice core are evidence of violent volcanic explosions (http://www.livescience.com/30507-volcanoes-biggest-history.html) that occurred about 22,470 and 45,381 years ago, near the West Antarctic divide. Their source, however, is a mystery.
The closest active volcanoes that rise above the ice are more than 185 miles (300 kilometers) away, said study leader Nels Iverson, a volcanologist and graduate student at the New Mexico Institute of Mining and Technology in Socorro. Powerful eruptions from these peaks (http://www.livescience.com/43990-antarctica-ice-age-refuges-volcanoes.html) have dusted the West Antarctica divide with ash, leaving glassy shards embedded in younger layers of the ice core. However, the ash particles described here Monday are too blocky and coarse to travel long distances, even on Antarctica's fierce winds. The ash is also chemically different from eruptions at the distant volcanoes. And to draw the circle in tighter, neither ash layer appears in an ice core drilled about 60 miles (100 km) to the southeast. [Fire and Ice: Images of Volcano-Ice Encounters (http://www.livescience.com/43902-volcano-ice-eruptions-photos.html)]
"It had to be from somewhere close," Iverson told Live Science. "Ash particles that travel far are shaped like little parachutes. These are like your fists trying to float on air."
Iverson said the rough, glassy shards embedded in the ice are typical of phreatomagmatic eruptions, the spectacular outbursts that occur when lava meets water. This kind of eruption killed 57 people at Japan's Mount Ontake volcano (http://www.livescience.com/48058-why-ontake-erupted-no-warning.html) in September, when water was superheated to steam. Similarly, when lava emerges under glaciers or ice caps, the molten rock melts ice into water and explodes, shattering lava into microscopic bits and flinging ash into the air.
Depending on the ice thickness and eruption size, it's possible for volcanic eruptions to have penetrated the West Antarctic Ice Sheet, said volcanologist Ben Edwards of Dickinson College in Pennsylvania, who was not involved in the study.
View gallery
http://l.yimg.com/bt/api/res/1.2/vtP9LENHUVVqLbAuJZWxcw--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTM5NDtxPTc1O3c9MzAw/http://media.zenfs.com/en_US/News/LiveScience.com/Phreatomagmatic-tephra.jpeg1418838724
(http://news.yahoo.com/photos/violent-volcanic-blasts-ripped-antarctic-ice-sheet-twice-photo-115608541.html)Blocky ash particles indicate a lava-ice eruption.
Magmas such as the basanite (an igneous rock) from the 45,000-year-old ash layer can melt three to six times their own mass in ice, he said. "The key thing is ice thickness," Edwards said. "Really thick ice makes it more difficult for the magma to explode."
Iverson suspects the volcanic source is buried close to the divide, where the ice sheet is more than 10,000 feet (3,050 meters) thick. There are three volcanoes entombed in ice within about 125 miles (200 km), and even more could be present.
Earthquakes suggest magma still churns beneath a previously unknown subglacial volcano in West Antarctica's Executive Committee Range, which was uncloaked when shaking started in 2010. Gravity and magnetic anomalies hint at nine subglacial volcanoes (http://www.livescience.com/41262-west-antarctica-new-volcano-discovered.html) near the West Antarctic divide, John Behrendt, a geologist at the University of Colorado, Boulder reported today (Dec. 17) at the meeting. Behrendt was not involved in the ice core study.
If a volcano erupts under the ice sheet, it could melt out millions of gallons of water, possibly destabilizing major glaciers. However, scientists don't yet agree on the potential effects of a subglacial eruption.
"We're trying to understand the implications for the stability of the ice sheet," Iverson said.
The West Antarctic Ice Sheet grew up and around an abundance of active volcanoes. For instance, the coastal volcanoes Mount Berlin, Mount Takahe and Mount Siple have erupted some 20 times in the past 571,000 years, according to ash layers in ice cores. Geothermal heating (http://www.livescience.com/46194-volcanoes-melt-antarctic-glaciers.html) has cooked the bottom of the ice sheet in the vicinity of some ice-covered volcanoes, according to recent studies. For instance, at the West Antarctic divide drilling site, researchers recovered about 70,000 years of ice, not 100,000 years as was expected, because the bedrock was hotter than they had assumed.
Follow Becky Oskin @beckyoskin (https://twitter.com/beckyoskin). Follow Live Science @livescience (https://twitter.com/LiveScience), Facebook (http://www.facebook.com/#!/livescience) & Google+ (https://plus.google.com/101164570444913213957/posts). Originally published on Live Science (http://www.livescience.com/49167-antarctica-volcanoes-erupted-through-ice.html).
The World's Five Most Active Volcanoes (http://www.livescience.com/29790-worlds-five-most-active-volcanoes.html)
Album: Stunning Photos of Antarctic Ice (http://www.livescience.com/11259-ice-antarctic.html)
50 Amazing Facts About Antarctica (http://www.livescience.com/43881-amazing-antarctica-facts.html)
Copyright 2014 LiveScience (http://www.livescience.com/), a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Nature & Environment
Natural Phenomena
West Antarctic Ice Sheet
Click to view comments
View Comments (132)