Another Hit for the Cs? - Volcanoes in the Arctic

Laura

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cs 81 Feb 95 said:
A: ... Volcanic eruption under arctic ice in 1996.
Q: (T) Cool! (L) That ought to be a real zinger.
(T) That will bring us some floods then!
A: No. Weather causing increased evaporation...



Arctic Volcanoes Found Active at Unprecedented Depths

Kimberly Johnson

for National Geographic News

June 26, 2008

Buried under thick ice and frigid water, volcanic explosions are shaking the Arctic Ocean floor at depths previously thought impossible, according to a new study.

Using robot-operated submarines, researchers have found deposits of glassy rock—evidence of eruptions—scattered over more than 5 square miles (15 square kilometers) of the seabed.

Explosive volcanic eruptions were not thought to be possible at depths below the critical pressure for steam formation, or 2 miles (3,000 meters). The deposits, however, were found at seafloor depths greater than 2.5 miles (4 kilometers).

"This kind of implosive seismicity is rare anywhere on Earth," said study author Robert Sohn, a geophysicist at the Massachusetts-based Woods Hole Oceanographic Institution.

The study appears today in the Journal Nature.

Anatomy of a Mid-Ocean Ridge

Seismic activity was previously detected in the same region in 1999, along the Gakkel Ridge—a 1,200-mile-long (2,000-kilometer-long) mid-ocean mountain range north of Greenland.

Hundreds of earthquakes were observed over a nine-month period, with magnitudes between 4 and 6.

This earthquake swarm was the largest in recorded history along a spreading mid-ocean ridge and prompted researchers to return to the area for further investigation.

In 2007 Sohn and his team stumbled across the glassy pyroclastic rock deposits while searching for hydrothermal vent fields in the Gakkel Ridge.

Powerful eruptions sent a plume of carbon dioxide, helium, and liquid lava up into the Arctic waters. When the material cooled, rock debris fell to the ocean floor, he explained.

Mid-ocean ridges are formed as hot molten material from inside Earth seeps into and fills the opening between two spreading tectonic plates. The Gakkel Ridge is considered an ultraslow spreading ridge because its plates spread at a rate of 0.4 inch (1 centimeter) a year.
 

Juba

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Somehow I have strong impression these eruptions are just "opening title" of much bigger drama. Imagine super calderas of Yellowstone, Awasa, Pastos Grandes or Lake Toba to erupt, even eruption of one single super volcano could change planetary climate to ice age in less than one month :scared:.
 
I live inside a super caldera on the Gold Coast in QLD. The plug of this long dormant super volcano is Mt.Warning, an aboriginal sacred site.
 

Laura

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wanderer33 said:
I live inside a super caldera on the Gold Coast in QLD. The plug of this long dormant super volcano is Mt.Warning, an aboriginal sacred site.

Have you researched the geological history of the area, particularly during Ice Ages?
 

Lindenlea

The Living Force
I live inside a super caldera on the Gold Coast in QLD. The plug of this long dormant super volcano is Mt.Warning, an aboriginal sacred site.

Wanderer33,

I have a block of land approx 50K, as the crow flies, dead South of Mt Warning, is this area also in the caldera? Sounds like you are about 20-40K North or NE.

Laura,

I know your request for geological history was directed to Wanderer33, but whilst I was checking it out on Wiki, I thought I would post this too.

_http://en.wikipedia.org/wiki/Mount_Warning

Shield volcano
Main article: Tweed Volcano

Mount Warning is the central volcanic remnant of an ancient shield volcano, the Tweed Volcano, which would have been about 1,900 m (6,200 ft) above sea level or just under twice the height of the current mountain.[4] This volcano erupted around 23 million years ago.[5] As the mountain's central vent cooled it shrank, forming a depression at the top that has greatly eroded.[4]

Today the vast areas that were part of the volcano include many mountains and ranges at some distance from Mount Warning, and include the Border Ranges, Tamborine Mountain, the McPherson Range and both the Lamington Plateau and Springbrook Plateaus. The erosion caldera formed since this eruption is easily visible around the summit and forms the rim of the Tweed Valley.

During the last stages of eruption, different and more resistant forms of lava that were cooler than those flows that created the shield volcano remained to form the current peak. The whole central Mount Warning massif was also pushed up by forces that remained active after lava eruptions had stopped.
 
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