Skip to comments.Way Under the Sea, Violent Eruptions From Volcanoes
Posted on 07/12/2008 8:51:22 PM PDT by neverdem
In 1999, seismographs detected a swarm of earthquakes at a spot on the Gakkel ridge, a midocean ridge that traverses the Arctic. A few expeditions to the area, north of Siberia about 350 miles from the pole, produced indirect evidence of explosive eruptions deep on the seafloor.
Explosive volcanism at such depths would be very unusual, said Robert A. Sohn of the Woods Hole Oceanographic Institution in Massachusetts. People had been afraid to even suggest it, because it seemed so ludicrous.
Seafloor volcanoes do erupt violently, but in relatively shallow water. The Gakkel ridge spot is 13,000 feet down, and at such great depths it had been thought that explosive eruptions could not occur because there is not enough gas in magma to overcome the immense pressure.
So in 2007 Dr. Sohn led another expedition to the area, sending a homemade contraption down to the seafloor with high-definition video cameras and a sampling device. His teams findings, reported in Nature, show conclusively that explosive eruptions occurred.
The evidence came in the form of fresh pyroclastic deposits, small bits of volcanic rock, spread over an area greater than four square miles. The researchers even found evidence of Limu o Pele, fragments of the wall of an exploding bubble of magma. A map of the area created using sonar showed what appeared to be cratered volcanoes that probably were the focus points of the explosions...
Dr. Sohn said the work showed how much there is to be learned about what goes on along deep midocean ridges. For one thing, explosive volcanism like this involving the release of large amounts of carbon dioxide may not be so rare. Our community is going to embrace this pretty quickly as a research topic, he said.
(Excerpt) Read more at nytimes.com ...
Roughly 60% of the Earth's outer surface is composed of oceanic crust formed by volcanic processes at mid-ocean ridges. Although only a small fraction of this vast volcanic terrain has been visually surveyed or sampled, the available evidence suggests that explosive eruptions are rare on mid-ocean ridges, particularly at depths below the critical point for seawater (3,000 m)1. A pyroclastic deposit has never been observed on the sea floor below 3,000 m, presumably because the volatile content of mid-ocean-ridge basalts is generally too low to produce the gas fractions required for fragmenting a magma at such high hydrostatic pressure. We employed new deep submergence technologies during an International Polar Year expedition to the Gakkel ridge in the Arctic Basin at 85° E, to acquire photographic and video images of 'zero-age' volcanic terrain on this remote, ice-covered ridge. Here we present images revealing that the axial valley at 4,000 m water depth is blanketed with unconsolidated pyroclastic deposits, including bubble wall fragments (limu o Pele)2, covering a large (>10 km2) area. At least 13.5 wt% CO2 is necessary to fragment magma at these depths3, which is about tenfold the highest values previously measured in a mid-ocean-ridge basalt4. These observations raise important questions about the accumulation and discharge of magmatic volatiles at ultraslow spreading rates on the Gakkel ridge5 and demonstrate that large-scale pyroclastic activity is possible along even the deepest portions of the global mid-ocean ridge volcanic system.
You can access linked abstracts of references from that link.
I am going to get flamed for this sarcastic comment..... but here it goes....
It is all global warmings fault isn’t.... :)
I saw some pretty incredible footage on one of the “educational” channels a number of years ago of a volcano erupting under the ocean. After seeing that, it was a lot easier from me to understand things like El Nino and what the jugheads call “global warming.” I may be wrong but that molten lava spewing out into the ocean like that has to do something to the temperature of the water. Imagine what it would do to the ice above it.
Nope, its Global Warming the way Mother Nature intended it.
No, it's Bush's fault! /sarc
Calling AlGore. Calling AlGore. You have a phone call from 20,000 leagues under the sea Please go answer it! Oh, that’s right, your full of hot air and would rise. ;-)
...For one thing, explosive volcanism like this involving the release of large amounts of carbon dioxide may not be so rare. Our community is going to embrace this pretty quickly as a research topic, he said...
The velocity of the embrace is proportional to how well it agrees with the Current Wisdom.
It is all global warmings fault isnt.... :)
You bet your sweet bippy it is or Geo. W's fault.
However, since there is no such thing as "global warming" except in the fertile minds of the Algores of the world---this article is interesting and a matter of oceanographic research; but in the day to day mindlessness of the Chicken Littles of GW persuasion---so what!
“I may be wrong but that molten lava spewing out into the ocean like that has to do something to the temperature of the water. “
Just like a giant aquarium heater.
So now we know why the ice is melting in some areas. (while increasing in others)
FReepmail me if you want on or off my health and science ping list.
The shocking thing about this article is that it is in the NY Times. One would expect that liberal rag to bury any reporting explaining the true cause of the Arctic ice melting.
Very interesting ,,,thanks.,
But what about the Gorwellian Concensus on CO2?
The carbon budget changed,
Human contribution to co2 increased levels are now substantially reduced with this finding.
Time to DRILL DRILL DRILL!
I'm not so sure. I think there are a lot of embarrassed scientists who are looking for an objective way to change their minds about global warming.
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