Underwater Volcanism

[Turtle]

We start with one eruption, and then build from there. What do we know about underwater volcanoes, and what do we not? ........

Underwater - Submarine Volcanoes

May 20, 2000 - Reuters
In the Pacific Ocean there are ocean basins - volcanoes, of which there are estimated to be about 20,000 on the ocean bottoms of the world. Some of these form single mountains, and others join with other volcanoes to form ridges. The highest ones rise above the surface of the water as islands, which in many cases linear groups such as the Hawaiian Islands.
...
Marine geologists have reported that a newly discovered undersea volcano east of Samoa is erupting, sending out a five-mile cloud of "smoggy" water from its summit.

Local students recently named the volcano, located 28 miles east of Taiu Island, 'Vailulu'u'. The volcano rises up more than 16,400 feet from the seabed to within 2,000 feet of the ocean's surface.

Scientists from Scripps Institution of Oceanography and the Woods Hole Oceanographic Institution first mapped the volcano during a research cruise in 1999. They returned this spring to find the volcano erupting. Anthony Koppers, a scientist at Scripps who studies undersea volcanoes, said the find was exciting because so few of the world's undersea volcanoes are accessible to study. He said, "We have access to the buildup of a volcano that will eventually become an island."

[Turtle]

Staying with Vailulu'u undersea volcano:.......................

Global Volcanism Program | Vailulu'u | Summary

On July 10, 1973, explosions from Vailulu'u were recorded by SOFAR (hydrophone records of underwater acoustic signals). An earthquake swarm in 1995 may have been related to an eruption from the seamount. Turbid water above the summit shows evidence of ongoing hydrothermal plume activity. ...

[Turtle]

A bit more with Vailulu'u undersea volcano: a moat of death, only a volcano Mother could love. .......................

Giant Deep-Sea Volcano With "Moat of Death" Found

Moat of Death

The moat lies between Vailulu'u's encircling crater and the rim of the cone inside it.

It's an extremely toxic environment, Staudigel said, where oxygen levels are dangerously low and volcanic vents fill the water with iron soot "almost like underwater smog."

The volcano is also spewing liquid carbon dioxide, which combines with seawater to make a deadly acidic mix. ...

[freeztar]

Hmmm...iron soot eh? No mention of H2....hmmmm...

[Turtle]

Originally Posted by freeztar

Hmmm...iron soot eh? No mention of H2....hmmmm...

Sorry if my chemistry is a little oxidized; please bear with me. There is plenty o' H down on the volcano, but as far as I've found it is not there as a free gas. I have to check some more to see what rocks may have it, but there is a lot tied up with sulphur as hydrogen-sulphide which the colonies of bacteria feed on.

Without regard to any specific links, undersea volcanoes aren't our Mommies' terestrial type I am finding. Hydration to who laid the chunk, enormous pressure, sodium, complex interconnected biotic systems, high temperature variances, and the physical structure of erupted lava, to name a few differences I have found so far.

[Turtle]

Originally Posted by agu.org

... The outflow water was typically warmer by 0.1-0.2 C; the maximum temperature range was 0.6 C, about half of that observed at the NW breach. A 12-hour continuous profiling CTD-LBSS station was serendipitously sited on top of a large diffuse-venting hydrothermal field, in the crater moat just north of the new volcanic cone. The water column here was incredibly dynamic, with a 5-10m bottom boundary layer, 1 C above ambient, forming by diffuse flow from the basalt substrate in a matter of minutes; this layer would destabilize, detach, and rise with velocities of ~ 1 cm/sec. This buoyant water was both warmer and less saline than either the ambient crater water, or the cold outside water which occasionally cascaded onto this site from the nearby NW breach; it was also laden with particulates, with LBSS readings up to 1.7 NTU. Water chemistry and He isotope analyses are in progress. ...

This bit above is still on Vailulu'u volcano, or actually the new 300 meter high volcanic cone, named Nafanua formed in its crater. The quote is from an abstract down this page; try not to get lost on the other underwater volcano info you pass on the way. ................ Seamount Hydrothermal Systems: Volcanology, Biology, Geochemistry, and Oceanography II Posters - Volcanology, Geochemistry, Petrology [V]

[Turtle]

Originally Posted by freeztar

Hmmm...iron soot eh? No mention of H2....hmmmm...

Just to revisit this for my clarification. When you say "H2", do you mean 'molecular' ('free'?) hydrogen as opposed to hydrogen compounds?

In the mean time, here's some more juicy bits on Vailulu'u: >>

UCSD Science & Engineering

Originally Posted by ucsdnews

The timing of Vailulu’u’s volcanic activity is close to events that have been recorded by global seismic networks. Major earthquake activity was recorded at or near Vailulu’u in July 1973 and January 1995. The authors say it is quite possible that these two seismic swarms were related to the eruptions that produced their dated rock samples.

Using isotopic tracing techniques, the scientists determined that the volcano was formed by partial melting of materials in the earth’s mantle with a characteristically "Samoan" composition or pedigree. The examinations suggested volcanic activity within the past 5 to 50 years, further evidence that Vailulu’u is the current location of the Samoan hot spot.

As an interesting sidelight, the evidence for volcanic activity at Vailulu’u may have an historical antecedent in Samoan mythology. Kanaloa, the oldest Polynesian volcano god, is said to have been involved in a violent battle to the East of Ta’u after which he landed on its eastern slopes. The site of his landing was honored with a temple to Kanaloa, built about 3,000 years ago. This temple faces the site of Kanaloa’s battle, and current location of Vailulu’u. Perhaps the ancient Polynesians knew about Vailulu’u all along? ...

Post Script: I simply can't not move on to some other underwater volcanoes of interest.



New Underwater Volcano Found, Discovered Off Coast Of Antarctica 900 Feet Down - CBS News

Originally Posted by AP

WASHINGTON, May 20, 2004
(AP) A previously unknown underwater volcano has been discovered off the coast of Antarctica, the National Science Foundation said Thursday.

The finding helps explain mariners' historical reports of discolored water in the area, the agency said. Material from underwater volcanoes is known to cause discoloration in water over them.
...
Highly sensitive temperature probes moving continuously across the bottom of the volcano showed signs of geothermal heating of seawater, according to the agency.

Domack said the volcano stands 2,300 feet above the seafloor and extends to within roughly 900 feet of the ocean surface.

The volcano is in an area known as Antarctic Sound, at the northernmost tip of Antarctica. There is no previous scientific record of active volcanoes in the region where the new peak was discovered. The volcano is located on the continental shelf, in the vicinity of a deep trough carved out by glaciers passing across the seafloor.

[freeztar]

Originally Posted by Turtle

Just to revisit this for my clarification. When you say "H2", do you mean 'molecular' ('free'?) hydrogen as opposed to hydrogen compounds?

Yes, "free", unbonded hydrogen. I realize that methane and h20 is vented.
It was meant as a sarcastic comment directed towards another thread (of which I'm sure you're aware of the referenced thread).

[Turtle]

Originally Posted by freeztar

Yes, "free", unbonded hydrogen. I realize that methane and h20 is vented.
It was meant as a sarcastic comment directed towards another thread (of which I'm sure you're aware of the referenced thread).

Roger. Moving back briefly to the liquid CO2 that Vailulu’u is putting out:

The volcano is also spewing liquid carbon dioxide, which combines with seawater to make a deadly acidic mix.

I gather from this that no molecular CO2 is getting to the atmosphere? What acids does it make, do you know?

Keep looking down.

[freeztar]

Originally Posted by Turtle

I gather from this that no molecular CO2 is getting to the atmosphere? What acids does it make, do you know?

I'm sure that some of it escapes the ocean, but it would be nice to quantify it.
Carbonic acid is the acid produced, but it seems quite unstable.

Originally Posted by wiki

It has since been shown, by theoretical calculations, that the presence of even a single molecule of water causes carbonic acid to revert to carbon dioxide and water fairly quickly. Pure carbonic acid is predicted to be stable in the gas phase, in the absence of water, with a calculated half-life of 180,000 years.

I just found this tasty morsel. Does under-ice count as under-water?
Press Release - First evidence of under-ice volcanic eruption in Antarctica - British Antarctic Survey

“This eruption occurred close to Pine Island Glacier on the West Antarctic Ice Sheet. The flow of this glacier towards the coast has speeded up in recent decades and it may be possible that heat from the volcano has caused some of that acceleration. However, it cannot explain the more widespread thinning of West Antarctic glaciers that together are contributing nearly 0.2mm per year to sea-level rise. This wider change most probably has its origin in warming ocean waters.”