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Blobrana


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Undersea volcano
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Similar volcanoes erupted during Precambrian time (about 1.7 billion years ago) in what is now Arizona. Some of them produced mineral deposits called volcanogenic massive sulphide deposits that contain copper, zinc, lead, silver, and gold. About a dozen such deposits occurring in northern Arizona have had some production, the largest known of which is the United Verde mine at Jerome.
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Blobrana


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RE: Brimstone Pit
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Scientists capture deepest underwater volcanic eruption on film



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Blobrana


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Extraordinary video has been obtained in the Pacific Ocean of the deepest undersea eruption ever recorded.
The pictures show lavas bursting into the water at the West Mata submarine volcano, which is sited about 200km south-west of the Samoas.
The US Jason robotic submersible had to descend over 1,100m to acquire the high definition video.
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Blobrana


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NW Rota-1 Submarine Volcano
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Marine Scientists Return From Expedition to Erupting Undersea Volcano
Scientists who have just returned from an expedition to an erupting undersea volcano near the Island of Guam report that the volcano appears to be continuously active, has grown considerably in size during the past three years, and its activity supports a unique biological community thriving despite the eruptions.
An international science team on the expedition, funded by the National Science Foundation (NSF), captured dramatic new information about the eruptive activity of NW Rota-1.

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Blobrana


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Neptunian eruptions
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Title: Products of neptunian eruptions
Authors: Sharon R. Allen and Jocelyn McPhie

A common pyroclastic facies in subaqueous volcanic successions comprises massive to graded, very thick (several to tens of meters), laterally extensive (several kilometres) beds of nonwelded pumice lapilli with volumes ranging to tens of cubic kilometres. This facies may be overlain by laminated ash or bimodal ash and giant (>1 m) pumice clasts, and underlain by coarse lithic breccia. The association is inferred to be the typical product of sustained magmatic volatiledriven explosive eruptions from vents at water depths of ~1300200 m. We propose the term neptunian for such eruptions and their products. The eruption column rapidly mixes with the surrounding water, cools, increases in density, and collapses, while remaining under water. Lithic clasts that are too heavy to be entrained in the column are deposited close to the source, forming a neptunian lithic breccia. Pumice lapilli are rapidly waterlogged and form the dominant component in the collapsing column and in eruption-fed, water-supported density currents (neptunian density currents). Hot, buoyant, giant pumice clasts continue to rise and may reach the water surface before being waterlogged and settling, along with temporarily suspended ash, forming neptunian suspension deposits. Eruption magnitude, fragmentation mechanisms, and juvenile pyroclast characteristics, especially vesicularity, are very similar in neptunian and Plinian-style eruptions, but column behaviour differs primarily because of the contrasting physical properties of the ambient fluid (water versus air).

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Blobrana


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RE: Brimstone Pit
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Scientists who have just returned from studying an erupting undersea volcano near the Island of Guam report that the volcano appears to be continuously active, has grown considerably in size during the past three years and its activity supports a unique biological community that is thriving despite the eruptions.
An international science team on the expedition, which was funded by the National Science Foundation, captured dramatic new video of the eruptive activity of NW Rota-1, which remains the only place on Earth where a deep submarine volcano has ever been directly observed while erupting.

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Blobrana


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Posts: 131433
Date:
NW Rota-1 volcano
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Scientists who have just returned from an expedition to an erupting undersea volcano near the Island of Guam report that the volcano appears to be continuously active, has grown considerably in size during the past three years, and its activity supports a unique biological community thriving despite the eruptions.
An international science team on the expedition captured dramatic new information about the eruptive activity of NW Rota-1.

"This research allows us, for the first time, to study undersea volcanoes in detail and close up. NW Rota-1 remains the only place on Earth where a deep submarine volcano has ever been directly observed while erupting" - Barbara Ransom, program director in NSF's Division of Ocean Sciences, which funded the research.

Scientists first observed eruptions at NW Rota-1 in 2004 and again in 2006, said Bill Chadwick, an Oregon State University (OSU) volcanologist and chief investigator on the expedition. This time, however, they discovered that the volcano had built a new cone 40 meters high and 300 meters wide.

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Submarine Ring of Fire 2006: NW Rota1 Brimstone Pit Erupting


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Blobrana


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RE: Brimstone Pit
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Previous surveys had identified a number of hydrothermal systems (plumes) on the arc volcanoes.
Chemical analysis of the plumes in 2003 found high concentrations of particulate aluminium, sulphur, iron, and manganese, along with elevated 3He, a helium isotope considered diagnostic of a magmatic source and associated hydrothermal discharge.
The active crater's summit depth was then ~ 517 m.

brimstone pit satellite

Position 14°36.048'N, 144°46.519'E

brimstone pit

Movie link

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Blobrana


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A team of scientists returned this month with new and dramatic video and sound recordings of an ongoing volcanic eruption underneath the deceptively calm waters of Rota Island in the Northern Mariana Islands.

Video of billowing ash plumes, molten sulphur droplets, and red lava jetting from a vent are just some of the new materials that the NOAA-led team of ocean explorers have of this long-term deep-sea volcanic eruption that was first discovered in 2004.
The eruption is at Brimstone Pit, a vent high on the side of the large submarine volcano called NW Rota-1, located (Position 14°36.048'N, 144°46.519'E)about 37 miles northwest of the island of Rota, in the Northern Mariana Islands.
The volcano is one of many on the Mariana Arc, part of the "Submarine Ring of Fire" that circles the Pacific Ocean basin, where tectonic plates spread or collide.

"In three international expeditions spanning more than two years, we've discovered a submarine volcano erupting perhaps continuously and often violently, spewing rocks that sometimes forced us to back away our remotely operated vehicles. But with those underwater robots, we could often get in close to take compelling images and to sample the chemistry in ways not possible with volcanoes on land" - Bob Embley, oceanographer with the NOAA Pacific Marine Environmental Laboratory in Newport, Ore., and chief scientist on missions in 2004 and 2006.

The 2006 Submarine Ring of Fire expedition from April 18 to May 13, 2006, is the third in a series of explorations of the submarine volcanoes lying along the Mariana Arc, extending from south of the island of Guam northward more than 800 nautical miles (1,450 km).

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