Royal New Zealand Navy finds huge floating pumice field in Pacific; Monowai Seamount volcano thought to have erupted

This news item is certainly fascinating, and there’s another fascinating observation in the stories that follow the leading one by CNN.

I think they’re quite noticeable.

See if you notice them.

Observations follow at the conclusion.

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‘Weirdest thing’ floats in South Pacific

By Todd Sperry, CNN
updated 10:36 PM EDT, Fri August 10, 2012

Officials reported the floating rock shelf to be 250 nautical miles long by 30 nautical miles wide.

(CNN) — Pumice, the lightweight stone used to smooth skin, is usually found in beauty salons, but on Thursday sailors from New Zealand‘s Royal Navy found nearly 10,000 square miles of the lava rock bobbing on the surface of the South Pacific Ocean.

By comparison, the state of Rhode Island comprises approximately 1,200 square miles.

Described by one sailor who witnessed it as “the weirdest thing I’ve seen in 18 years at sea,” the sea of white rock was initially spotted by air and then relayed to a ship for further investigation, according to a statement released by the New Zealand Royal Navy.

“The lookout reported a shadow on the ocean ahead of us, so I ordered the ship’s spotlight to be trained on the area … as far ahead as I could observe was a raft of pumice moving up and down with the swell,” Lt. Tim Oscar said.

Pumice is typically a byproduct of lava that has cooled quickly after a volcanic eruption. The lava forms a rock so lightweight it floats on the water’s surface.

“As we moved through the raft of pumice we used the spotlights to try and find the edge — but it extended as far as we could see,” Oscar said after the encounter.

Officials reported the floating rock shelf to be 250 nautical miles long by 30 nautical miles wide. A nautical mile is about 6,076 feet.

“The rock looked to be sitting two feet above the surface of the waves, and lit up a brilliant white color in the spotlight. It looked exactly like the edge of an ice shelf,” Oscar said, according to the statement.

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Sailors said taking their ship directly into the floating pumice to gather samples for research scientists didn’t put the vessel at risk because the rock was so lightweight.

Volcanologist Helen Bostock told New Zealand Royal Navy officials the rock came from an underwater volcanic eruption, and now scientists will work to determine which volcano was responsible.

According to scientists who briefed Navy officials, a volcano named Monowai has been active in the region and the pumice could be a result of recent eruptions.

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http://www.cnn.com/2012/08/10/world/asia/floating-pumice/index.html

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Undersea eruption creates pumice raft

New Zealand scientists are investigating an undersea volcanic eruption which has created a large “pumice raft” 400km west of Raoul Island.

GNS Science vulcanologist Craig Miller told NZ Newswire that the Royal New Zealand Air Force has provided photographs of the pumice raft and New Zealand’s National Maritime Coordination Centre has reported a sea disturbance 100 nautical miles long and 25 nautical miles wide, located 400km west of Raoul Island.

It was originally thought that the undersea volcano Monowai had erupted but it’s northeast of Raoul Island.

Helen Bostock holds some of the pumice discovered South West of Raoul Island. An area of floating pumice 250 nautical miles in length and 30 nautical miles wide was spotted South West of Raoul island yesterday. An RNZAF Orion on Maritime patrol from Samoa to New Zealand spotted the pumice. According to GNS science the underwater volcano Monowai has been active along the Kermadec Arc and the pumice could be a result of that activity. HMNZS CANTERBURY is on passage from Auckland to Raoul Island in the Kermadec group with a party of GNS scientists onboard. The Commanding Officer, Commander Sean Stewart changed course to intercept the pumice and bought the ship to a halt to enable retrieval of samples. The samples will be analysed to determine which volcano they came from. According to GNS scientists the activity at volcano’s at Tongariro, White Island and along the Kermadec arc is unrelated.

Mr Miller said the pumice raft has been caused by an undersea eruption.

When magma flows into the sea it quickly cools and turns into pumice and then floats to the surface.

Asked if the undersea eruption was linked to the eruption of Mt Tongariro and an eruption on White Island this week he said: “It’s all along the same boundary but that is about where the link stops”.

The navy vessel Canterbury has picked up samples of the pumice and GNS scientists are on board the vessel.

Raoul Island is part of Kermadec Islands and is 1100km northeast of New Zealand. The area is a known source of volcanic activity.

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http://www.3news.co.nz/Undersea-eruption-creates-pumice-raft/tabid/1160/articleID/264973/Default.aspx

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Raft of pumice floats off New Zealand

Published: 6:04PM Friday August 10, 2012 Source: ONE News

A navy ship sailing towards the Kermadec Islands has encountered a 25,000 square kilometre area of pumice pieces.

The area of floating pumice was estimated to be 250 nautical miles in length and 30 nautical miles wide.

The Royal New Zealand Air Force (RNZAF) Orion spotted the phenomenon yesterday afternoon, while on maritime patrol from Samoa to New Zealand.

The area of floating pumice is about 85 nautical miles off West South-West of Raoul Island.

Lieutenant Tim Oscar, a Royal Australian Navy officer described the phenomenon as “the weirdest thing I’ve seen in 18 years at sea”.

He said the raft of pumice was moving up and down with the swell as far ahead as he could observe.

“The rock looked to be sitting two feet above the surface of the waves, and lit up a brilliant white colour in the spotlight. It looked exactly like the edge of an ice shelf,” said Oscar.

RNZAF staff had been briefed by GNS Volcanologist Helen Bostock the previous day when the ship first encountered an area of pumice from an undersea volcano, believed to be New Zealand’s third erupting volcano –  the undersea Mount Monowai.

“I knew the pumice was lightweight and posed no danger to the ship. None-the-less it was quite daunting to be moving toward it at 14 knots.

“It took about 3 – 4 minutes to travel through the raft of pumice and as predicted there was no damage. As we moved through the raft of pumice we used the spotlights to try and find the edge – but it extended as far as we could see,” said Oscar.

The Commanding Officer, Commander Sean Stewart changed course to intercept the pumice, and brought the ship to a halt to enable retrieval of samples.

The samples will be analysed to determine which volcano they came from.

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http://tvnz.co.nz/national-news/raft-pumice-floats-off-new-zealand-5017228

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Monowai, 3rd volcano thought to have erupted

August 10, 2012 | Filed under: Editor’s Pick,Lastest News,Whanau, Hapu, Iwi, Marae | Posted by: DigitalMaori

25,000 sq km sea of pumice floats off New Zealand

(By MICHAEL FIELD AND STACEY KIRK, Stuff.co.nz)

A navy ship heading to the Kermadec Islands has sailed into a huge 25,000 square kilometre area of pumice pieces north of Auckland.

It is believed to be from New Zealand’s third erupting volcano – the undersea mount Monowai. In the past week both Mt Tongariro and White Island have erupted.

The navy said the raft – 463 kilometres by 55 kilometres – was spotted by an RNZAF Orion returning on patrol from Samoa.

Canterbury, which left Auckland on Wednesday, sailed to the raft to pick up a sample.

GNS scientists are aboard the ship, which is also carrying 30 high school students on a Sir Peter Blake fellowship to Raoul Island.

GNS vulcanologist Craig Miller said they were aware of the ”pumice raft” but did not know the exact dimensions of it.

He said it was difficult to guess how big the pumice raft could be, but the air force had flown over and assessed its size.

“We’ve been in contact with the air force recently about it. But it is floating more than 1000 kilometres offshore, so it’s a while away.”

Miller said the pumice raft was about “half way to Tonga”, and just past Raoul Island.

A science writer on the voyage to the Kermadecs has been keeping a journal of findings from each day.

Rebecca Priestley said it was “an event” which caused the Canterbury’s Commanding Officer, Commander Sean Stewart to give the order to change course.

“Up to 250 nautical miles long by 30 nautical miles wide, it stood out against the blue-grey of the ocean as a great white froth on the surface of the sea,” Priestley wrote.

She said they came across it about midday yesterday.

Navy ratings reportedly lowered buckets, tied to a rope, off the gun deck and down into the water to collect deposits, which Marine Geologist Helen Bostock, who is also on the voyage, would take back to Niwa to examine, Priestly said.

About Monowai

Monowai is a volcanic seamount to the north of New Zealand. It is one of the most active volcanoes in the Kermadec volcanic arc.

The most recent eruptions were in 2008 and 2011.

The summit is approximately 132 metres (433 ft) below sea level, considerably above the level of the nearby Tonga and Kermadec Trenches. The summit’s position and depth changed between 1998 and 2004, due to a landslide and eruptive regrowth. A 1500 metre deep caldera, 13 by 8 km, lies 5–15 km NNE of the seamount’s main cone.

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http://news.tangatawhenua.com/archives/18727

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Monowai Seamount

Map view shows Monowai submarine volcano at the lower left, with subsidiary cones on its northern flank. A large submarine caldera lies at the upper right lies to the NE. The contour interval is 100 meters, and the resolution of the bathymetry data is 25 meters. The proprietary bathymetry data were obtained by scientists of the New Zealand National Institute of Water and Atmospheric Research (NIWA) during a 2005 New Zealand/American NOAA Ocean Explorer research expedition to the Kermadec-Tonga arc. Image courtesy of Ian Wright, 2005 (NIWA; http://oceanexplorer.noaa.gov/explorations/05fire).

Monowai seamount, also known as Orion seamount, rises to within 100 m of the sea surface about halfway between the Kermadec and Tonga island groups. The volcano lies at the southern end of the Tonga Ridge and is slightly offset from the Kermadec volcanoes. Small parasitic cones occur on the north and west flanks of the basaltic submarine volcano, which rises from a depth of about 1500 m and was named for one of the New Zealand Navy bathymetric survey ships that documented its morphology. A large 8.5 x 11 km wide submarine caldera with a depth of more than 1500 m lies to the NNE. Numerous eruptions from Monowai have been detected from submarine acoustic signals since it was first recognized as a volcano in 1977. A shoal that had been reported in 1944 may have been a pumice raft or water disturbance due to degassing. Surface observations have included water discoloration, vigorous gas bubbling, and areas of upwelling water, sometimes accompanied by rumbling noises.

Country:	New Zealand
Subregion Name:	Kermadec Islands
Volcano Number:	0402-05-
Volcano Type:	Submarine volcano
Volcano Status:	Historical
Last Known Eruption:	2008
Summit Elevation:	-132 m	– 433 feet
Latitude:	25.887°S	25°53’15″S
Longitude:	177.188°W	177°11’17″W

http://www.volcano.si.edu/world/volcano.cfm?vnum=0402-05-

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Monowai Seamount as seen on Google Earth

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Additional information on the Monowai Seamount – index of monthly reports – may be found at: http://www.volcano.si.edu/world/volcano.cfm?vnum=0402-05-&volpage=var

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Presumed Floating Pumice

Tonga, SW Pacific Ocean

This report presents a serendipitous observation near Tofua, possibly indicative of volcanism elsewhere (not on Tofua). A photo of Tofua and vicinity from space taken on 13 April 2011 displays significant material on the sea surface – the possible relict of an eruption at some unknown center.

A photo taken from space by Astronaut Paulo Nespoli (figure 25) could suggest an eruption in the Southern Pacific region at an unknown volcano. Nespoli took the photo from the International Space Station on 13 April 2011 (Nespoli, 2011). It shows occasional white clouds over the island’s high points, and a thin gray-blue plume indicative of Tofua’s volcanic emissions wafting to the SE.

Figure 25. Photo taken 13 April 2011 from the International Space Station with hand-held camera showing Tofua and debris on the sea surface suggestive of pumice. The composition and source of the debris is unknown; however, the shape, distribution, and color of areas of debris are consistent with zones of floating pumice. Image (239B2033) courtesy of Astronaut Paolo Nespoli (European Space Agency and the International Space Station); labels and dashed lines added.

The elongate and sinuous bands of debris seen in the photo are suggestive of floating pumice seen before in the region (eg., see Home Reef, BGVN 31:09; 31:10; 31:12; 32:04; 33:05; 33:12; Metis Shoal, BGVN 20:06). If this is pumice in elongate strands such as seen from Home Reef’s 2006 eruption, it could also be derived from deposits of an older eruption. Debris floating in strands are most conspicuous at upper left of figure 25, where they form a curve cut by the photograph’s left edge. Faintly linked to that area is a thinner strand of sinuous debris. Other strands of similar width appear elsewhere.

Reference. Nespoli, P., 2011, Tofua Island, Tonga: Flickr (uploaded 18 April 2011) (URL: http://www.flickr.com/photos/magisstra/5618223635/).

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http://www.volcano.si.edu/reports/bulletin/contents.cfm?issue=3609&display=complete

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OBSERVATIONS:

The calculation of square area is determined by multiplying length x width. The area in the story was 250 x 30 = 7500. And 7500 square nautical miles is equivalent to 8630.8 square miles. That’s a far cry from the “nearly 10,000 square miles” cited by CNN. As a matter of fact, it’s almost the size of New Hampshire, which has 8,968.10 square miles. Or, if you prefer, it’s nearly as large as Rhode Island, Delaware and Connecticut combined (which is 7843.29 square miles.)

As well, the sailor cited by CNN in the sentence “Described by one sailor who witnessed it as “the weirdest thing I’ve seen in 18 years at sea…”” was not merely a sailor, but rather was Lieutenant Tim Oscar, a Royal Australian Navy officer.