[Turtle]

Here's a researchers log that gives a sense of the history, mystery, adventure, expense, and danger involved in investigating submarine volcanos & hydrothermal vents. Good photos as well.

Originally Posted by Institute for the Study of Earth, Oceans and Space

Follow UNH professor and researcher, Karen Von Damm, and her crew on leg 6 of voyage 7 on the R/V Atlantis, a Woods Hole Research Vessel. The following log is Karen Von Damm's e-mail from the R/V Atlantis . . .

Research Log
Introducton . . .
East Pacific Rise; 21°N latitude
Black smokers were first discovered in 1979 at a site known as "21° North"on the East Pacific Rise. We know the mid-ocean ridge is a giant volcano, and we know volcanoes can change quite quickly as the hot rock (lava) moves around below the Earth's surface and also erupts at the surface - whether on the seafloor or on land. (21°N is named for the latitude it occurs at.)

No one knows how long the sites on the seafloor where black smokers are found with their associated animal communities last. Going back to 21° North allows us to see how a system that we know has been operating for over 20 years has changed. The last time the hydrothermal fluids here were sampled ws 1992 - a decade ago. It has been very difficult to understand how fast things happen on the seafloor. Mostly it is believed to change very slowly, but as we have followed volcanic eruptions at a few sites on the seafloor, we have been amazed at the rapidity of the changes. As far as we know, there has been no eruption at 21°N in recent times. ...

Jan 9 2002

[Turtle]

The latest & greatest on the East Pacific Rise submarine volcanism.

Originally Posted by Larry O'Hanlon

Dec. 4, 2007 -- For the first time ever, scientists have the goods on a large volcanic eruption at the bottom of the ocean.

Putting together more than 50,000 sea floor images, along with 10 exploratory dives with the Alvin submarine, an unprecedented map has been pieced together showing 22 million cubic meters of new lava coming out of the East Pacific Rise -- a seafloor spreading center off the Pacific coast of Mexico.

The area covered by the recent eruption is equivalent to metropolitan Oklahoma City, or nearly half of Manhattan. The discovery that an eruption was underway, however, was sort of an accident.

"We had an array of seismometers down there that weren't coming back," said marine geophysicist Maya Tolstoy of Columbia University's Lamont-Doherty Earth Observatory. They were, in other words, buried by lava, she explained. ...

Discovery News : Discovery Channel

[Turtle]

Who says geologists don't have a sense of humor? Kick-'em-Jenny!!!???

Originally Posted by volcano.und.edu

Location: 12.3N, 61.6W
Kick-'em-Jenny is a submarine volcano located 6 miles (10 km) north of the island of Grenada. It is the southern-most active volcano in the Lesser Antilles volcanic arc and the only active submarine volcano in the arc.

Kick-'em-Jenny and the other volcanoes in the arc are associated with a subduction zone. The subduction zone is formed by an oceanic plate created at the Mid-Atlantic Ridge as it is pushed under the Caribbean Plate.

This figure is a geologic map of Kick-'em-Jenny by Sigurdsson and Shepherd (1974). Calle Island is made of two youthful craters and lava flows. Kick-'em-Jenny has erupted 10 times since 1939 with the most recent eruption in 1990. The 1939 eruption sent a black cloud up to 885 feet (270 m) above sea level. During the 1965 eruption, earthquakes of intensity V were felt on Isla de Ronde. ...

Kick-'em-Jenny, West Indies

[Turtle]

Something new & hot under the sea.

04/08/2008 Volcanologist Ármann Höskuldsson from the University of Iceland and a team of scientists recently discovered a more than 50-square-kilometer volcano off Reykjanes peninsula, southwest Iceland, and expect it to erupt at any time.
...
The volcano’s discovery is considered significant because geographers believed it couldn’t exist in that area. “Such large volcanoes are not located on oceanic ridges. They are always drifting apart and that prevents a volcano from being created. This is why the volcano’s existence came as a surprise,” Höskuldsson said. ...

Giant Underwater Volcano Discovered in Iceland >> Four Winds 10 - fourwinds10.com

[Turtle]

Some hot activity on the discovery of new submarine volcanoes front. Lobster!

Originally Posted by EScience News

Several huge active submarine volcanoes, spreading ridges and rift zones have been discovered northeast of Fiji by a team of Australian and American scientists aboard the Marine National Facility Research Vessel, Southern Surveyor. On the hunt for subsea volcanic and hot-spring activity, the team of geologists located the volcanoes while mapping previously uncharted areas. Using high-tech multi-beam sonar mapping equipment, digital images of the seafloor revealed the formerly unknown features.

The summits of two of the volcanoes, named 'Dugong', and 'Lobster', are dominated by large calderas at depths of 1100 and 1500 metres. ...

Active submarine volcanoes found near Fiji | Eureka! Science News

[freeztar]

You're going to love this one Turtle.

A research team led by the Woods Hole Oceanographic Institution (WHOI) has uncovered evidence of explosive volcanic eruptions deep beneath the ice-covered surface of the Arctic Ocean. Such violent eruptions of splintered, fragmented rock--known as pyroclastic deposits -- were not thought possible at great ocean depths because of the intense weight and pressure of water and because of the composition of seafloor magma and rock.

Researchers found jagged, glassy rock fragments spread out over a 10 square kilometer (4 square mile) area around a series of small volcanic craters about 4,000 meters (2.5 miles) below the sea surface. The volcanoes lie along the Gakkel Ridge, a remote and mostly unexplored section of the mid-ocean ridge system that runs through the Arctic Ocean.

Woods Hole Oceanographic Institution. "Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean." ScienceDaily 26 June 2008. 6 August 2008 <Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean>.

[Thunderbird]

This reminded me of an island I came across while I was exploring on Google Earth. This island’s land forms seemed a bit odd so I looked up the geology.

Macquarie Island lies in the southwest corner of the Pacific Ocean, about half-way between Australia and Antarctica. 54°37'53"S, 158°52'15"E.

Macquarie Island lies atop a geographic feature named for the island, the Macquarie Ridge. This seafloor ridge is aligned along the eastern margin of the tectonic plate boundary between the Indo-Australian Plate and the Pacific Plate.



Amazing geology
Macquarie Island is a geological wonder. The main reasons for its listing are its unique geological values.
It is the only island in the world composed entirely of oceanic crust and rocks from the mantle - deep below the earth's surface.


Macquarie Island probably began as a spreading ridge under the sea with the formation of new oceanic crust somewhere between 11 and 30 million years ago. At some stage the spreading halted and the crust began to compress, squeezing rocks from deep within the mantle upwards like toothpaste from a tube. As the ridge grew it eventually became exposed above the ocean's surface about 600,000 years ago.

For the first time, rocks normally only occurring deep within the earth's mantle have become exposed on the earth's surface.
Unlike other sub Antarctic islands which have been shaped by glaciers, once Macquarie Island emerged, it has mainly been carved by marine processes such as wave action.
The geodiversity of Macquarie Island provides the foundation for the landforms, soils, plants and animals occurring here. It is an island of unique natural diversity, a site of major geoconservation significance and one of the truly remarkable places on earth.
A Marine Ridge


Notice the slope of the mountain as it drops towards the sea? This slope continues underwater at the same rate. As a result, the sea floor is very deep just a few kilometres offshore. Macquarie Island is actually on the top of a marine mountain ridge.
Generally, landmasses (such as Australia) have a continental shelf which slopes gently offshore. This makes the sea floor close to shore quite shallow. However as Macquarie Island is on a mountain ridge, the seafloor drops away dramatically.
Macquarie Island provides evidence of the rock types found at great depths in the earth's crust but also for plate tectonics and continental drift, the geological processes which have dominated the earth's surface for many millions of years.


Macquarie Island is a geological wonder, a site of world significance. Rocks outcropping on the north of the island have been forced up from about 6 km below the ocean floor, a unique exposure of rocks from the earth's mantle technically known as ophiolites. No drill hole has penetrated these depths and so these exposures provide a rare opportunity to gain an understanding of geological processes from some of the deepest rocks in the earth.
The southern part of Macquarie Island is composed of rocks which are typical of those currently forming along mid-oceanic ridges that contribute directly to the process of continental drift. These ridges occur on the ocean bed, where lava erupts out of long fissures running for hundreds of thousands of kilometres across the major ocean floors. They are only visible above the sea floor at a few places such as Macquarie Island and Iceland.
Equally impressive is the island's ongoing rapid rise out of the sea making it one of the most active geological regions in Australia. This is obvious from landslide and earthquake activity on the island which has produced a landscape controlled by prominent faults, many of which are clearly evident as long ridges with very steep slopes on one side. The sea has also been responsible for shaping most of the island as it has risen above the waves, more recently cutting distinct shore platforms and sea stacks. These active processes, have continued since the Macquarie Ridge appeared above sea level just over half a million years ago.
Why is Macquarie different?
Macquarie has a number of special features.
Firstly there are no other subantarctic islands which have been squeezed upwards from the oceanic crust to form an island like this. Most subantarctic islands, including Heard Island, initially developed as underwater volcanoes. Some are now exposed above the sea as a result of the accumulation of layers of lava. Prince Edward Island, the McDonald Islands and Iles Crozet also formed from submarine volcanoes while Auckland and Campbell Islands have volcanic origins but they were previously attached to continents and the continental crust.
Secondly the rocks of Macquarie Island which are in their original (oceanic) geological setting, are far less deformed than similar rocks elsewhere. For example, the Troodus complex of Cyprus, the Semail complex of Iman and the Bay of Islands complex of Newfoundland although geologically similar to Macquarie Island are more deformed. These rocks have also been "welded" to continental type rocks, a process in which the rocks are squashed, stretched or both.
There is still considerable geological debate over whether the rocks in the complexes actually originated from the oceanic crust. Some geologists feel that they have formed in entirely different geological settings such as the volcanic islands around the Pacific rim where oceanic crust is being forced, or subducted, below the adjacent continent.
Macquarie Island is in a totally different geological setting to these islands but is considered to be very close to its original oceanic setting. It has not been forced up against the edge of a continent.

Macquarie Island -- Geology*

[Thunderbird]

Originally Posted by freeztar

You're going to love this one Turtle.



Woods Hole Oceanographic Institution. "Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean." ScienceDaily 26 June 2008. 6 August 2008 <Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean>.

Its always been a dream of mine to go rock hounding in Antarctica. It has meteors on top of the ice sheet, some the oldest metamorphic outcrops, fossil beds, and whole undescribed geology under the Ice that due to global warming is being exposed for the first time.

[Turtle]

Originally Posted by freeztar

You're going to love this one Turtle.



Woods Hole Oceanographic Institution. "Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean." ScienceDaily 26 June 2008. 6 August 2008 <Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean>.

You sure know how to coax a turtle out its shell.

Originally Posted by ScienceDaily

Making just the third expedition ever launched to the Gakkel Ridge--and the first to visually examine the seafloor--researchers used a combination of survey instruments, cameras, and a seafloor sampling platform to collect samples of rock and sediment, as well as dozens of hours of high-definition video. They saw rough shards and bits of basalt blanketing the seafloor and spread out in all directions from the volcanic craters they discovered and named Loke, Oden, and Thor.
...
To date, there have been scattered signs of pyroclastic volcanism in the sea, mostly in shallower water depths. Samples of sediment and rock collected on other expeditions have hinted at the possibilities at depths down to 3,000 meters, but the likelihood of explosive eruptions at greater depths seemed slim.

One reason is the tremendous pressure exerted by the weight of seawater, known as hydrostatic pressure. More importantly, it is very difficult to build up the amount of steam and carbon dioxide gas in the magma that would be required to explode a mass of rock up into the water column. (Far less energy is needed to do so in air.) In fact, the buildup of CO2 in magma in the sea crust would have to be ten times higher than anyone has ever observed in seafloor samples. ...

And this is a process I never heard of before:

Originally Posted by ScienceDaily

Closer analysis has shown that the some of the tiny fragments are angular bits of quenched glass known to volcanologists as limu o Pele, or "Pele's seaweed." These fragments are formed when lava is stretched thin around expanding gas bubbles during an explosion. ...

I'm still waiting & looking for any news of submarine volcanism off the Oregon coast; a possibility floated during the recent spate of offshore earthquakes.

Who'd a thunk it?

[Turtle]

I never found the specific location mentioned in that latest article. Anyway, we just had a 5.6 quake up on Gakkel Ridge. Eeeeeruption!!!?

Magnitude 5.6 - NORTH OF SEVERNAYA ZEMLYA