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Hunga Tonga-Hunga Ha’apai erupts 17 March 2009

Posted by admin in activity reports, eruptions, Pacific, submarine volcanism, Tonga.
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And what, precisely (you ask), is Hunga Tonga-Hunga Ha’apai? It is, or rather, they are, two islands that cap a large seamount in the Tonga Islands. Passengers and crew on a flight over the area witnessed a fresh eruption there yesterday, the first since 1988.

Blog post and pictures can be found here, and Eruptions has all the facts and background here.

Hunga venting on Thursday 18 March viewed from Kanokupolu Beach (photograph by Shane Egan, copyright Matangitonga.to).
Above: Plume from the Hunga Tonga-Hunga Ha’apai eruption viewed from Kanokupolu Beach, Nuku’alofa, 18 March 2009. Photograph by Shane Egan, copyright Matangi Tonga, used with permission. [source]

UPDATE, 18 March 2009. Various news sources have picked up the story and are listed below. Among the details reported are a possible connection to a magnitude 4.4 earthquake last Friday, 35km W of Tongan capital Nuku’alofa. In Tonga itself, Matangi Tonga has a detailed story with pictures of the eruption plume taken from Nuku’alofa. Stuff.co.nz reports that New Zealand air traffic is being disrupted by the eruption, and quotes an Airways New Zealand spokeswoman as saying that the volcano’s eruption column is reaching 15000 metres altitude. Wellington VAAC, however, currently reports ash at flight level 150, which is 15000 feet (4500 metres). The highest altitude they have reported the emissions reaching is flight level 250, 25000 feet, which is 7600 metres.

Click here for a satellite image of the eruption (MODIS/NASA Aqua).

The Hunga's volcanic eruption as seen from the Nuku'alofa waterfront (photograph by Pesi Fonua, copyright Matangitonga.to).
Above: Hunga Tonga-Hunga Ha’apai plume photographed from Nuku’alofa waterfront, 18 March 2009. Photograph by Pesi Fonua, copyright Matangi Tonga, used with permission. [source]

The plume from an underwater volcanic eruption goes up thousands of metres. Photo from Kanokupolu Beach by Shane Egan (copyright Matangitonga.to).
Above: Hunga Tonga-Hunga Ha’apai plume photographed from Kanokupolu Beach, Nuku’alofa, 18 March 2009. Photograph by Shane Egan, copyright Matangi Tonga, used with permission. [source]

Images from Matangi Tonga are reproduced here with the kind permission of Pesi Fonua, Publisher/Editor. The Volcanism Blog is very grateful for permission to use these images.

Information
Global Volcanism Program: Hunga Tonga-Hunga Ha’apai – summary information about Hunga Tonga-Hunga Ha’apai (0403-04=)
Tonga volcanoes and volcanics – overview from the USGS

News
Undersea volcano erupts off Tongan coast – Associated Press, 18 March 2009
Undersea volcano erupts off Tonga – ABC News, 18 March 2009
Underwater eruption close to Nuku’alofa – Matangi Tonga, 18 March 2009
Underwater volcano erupts near Tongan capital – ABC Radio Australia News, 18 March 2009
Deep sea volcano erupts off coast – 9 News, 18 March 2009
Volcanic eruption disrupts NZ flights – Stuff.co.nz, 19 March 2009

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New Zealand undersea volcanism at the Eruptions blog 12 March 2009

Posted by admin in current research, geoscience, New Zealand, submarine volcanism.
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Dr Klemetti has an interesting post at his Eruptions blog today on undersea volcanism in the Kermadec Arc, north of New Zealand. A study by the University of Southampton and the University of Washington found evidence of a high level of volcanic activity in this area, with the delightfully-named Rumble III volcano having apparently filled in its crater and lost 100m in height since 2007. Eruptions has all the information and relevant links: Volcanoes old and new in New Zealand.

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The Daily Volcano Quote: submarine volcanoes of the Azores, 1811 4 March 2009

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St. Michael’s, Aug. 2, 1811. For the last four months we have scarcely been three days together without experiencing shocks of an earthquake, more or less violent, which have done great damage to the buildings, and been injurious to the cultivators, but fortunately have not occasioned the loss of many lives. These shocks appear to have been produced by two or three volcanoes in the sea, at a short distance from this island, struggling for vent. One which is situated about three leagues from our coast, has ejected such a quantity of matter, that an island four miles long, and two and a half broad, has been formed; and it is still increasing — perhaps it may in time, by continued eruptions, be joined to our island. Another volcano appeared on the 4th July, about eight leagues distance, and in near 35 fathoms water. It has ejected much lava, and greatly agitated the sea, and will doubtless form an island; but its surface on the 28th was still below the level of the water. A third volcano is said to have been discovered a little to the eastward, of which the smoke is plainly visible from St. Michael’s. Some boatmen who approached it while quiescent, report, that the sea on the spot was quite discoloured, and had a sulphureous smell, and that they picked up a quantity of dead fish, half roasted. On the first island, vegetation, I am assured, is already apparent on one side.

‘Sub-Marine Volcanoes near the Azores’, The Observer, 29 September 1811, p. 3.

The Daily Volcano Quote: from Monday to Friday, a new eruption of volcanic verbiage each day.

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Tonga boulders may be evidence of volcanic tsunami 25 September 2008

Posted by admin in current research, geoscience, natural hazards, Pacific, submarine volcanism.
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Seven huge coral boulders standing on the western shore of Tonga’s main island Tongatapu may be evidence of a tsunami produced by a volcanic eruption, according to University of Texas researchers. The boulders, which are up to 9 metres high and weigh up to 1600 tonnes, are made of coral similar to that which makes up the offshore reefs of Tongatapu; their coral was formed about 122,000 years ago. They were clearly not formed in their present location and could not, on largely flat Tongatapu, have rolled downhill from somewhere else. The conclusion is that they were torn from the reef and hurled inland by a tsunami generated by a submarine eruption, probably from one of the volcanic centres in the northern section of the nearby Tonga-Kermadec Arc.

‘These could be the largest boulders displaced by a tsunami, worldwide’, says Matthew Hornbach of the University of Texas Institute for Geophysics. ‘We think studying erratic boulders is one way of getting better statistics on mega-tsunamis. There are a lot of places that have similar underwater volcanoes and people haven’t paid much attention to the threat’.

UPDATE: Dr Erik Klemetti at Eruptions takes a cautious look at the Tonga boulders: ‘it will be interesting to see what evidence they have for the deposit being from a volcanically-triggered event’.

UPDATE: National Geographic News has published an article on the Tonga boulders, which has been added to the list of links below.

[Found via Geology News.]

News
World’s largest tsunami debris discovered – ScienceDaily, 25 September 2008
Boulders on Tonga may have been dumped by tsunami – Reuters, 25 September 2008
Tongan coral may hold key to ancient tsunami – Radio Australia, 25 September 2008
Boulders in Tonga evidence of largest tsunami debris found – Geology News, 24 September 2008
The big boulders of Tonga – Eruptions, 25 September 2008
Ancient tsunami carried giant boulders to TongaNational Geographic News, 30 September 2008

Information
Global Volcanism Program: Tonga Islands – volcanoes of Tonga and vicinity
New Zealand American Submarine Ring of Fire 2005 – studying submarine volcanism in the Tonga-Kermadec Arc
Bathymetry of the Tonga Trench and Forearc: a map series – article, with maps, from Marine Geophysical Researches, vol. 21, no. 5 (2000)

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The shifting seabed: earthquakes off Vancouver Island 28 August 2008

Posted by admin in activity reports, geoscience, Pacific, submarine volcanism.
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Beneath the North Pacific off the coast of Canada and the north-western United States is one of the most complex tectonic situations on the planet, where the Juan de Fuca Plate is being subducted beneath North American Plate at the Cascadia Subduction Zone. The area is, as might be expected, highly seismically active (recently springing a seismic surprise with an earthquake swarm in the centre of the Juan de Fuca Plate, away from the plate’s boundaries), and is also very effectively monitored, thanks to the United States Navy SOSUS hydrophone network.

More interesting activity is currently under way on the Juan de Fuca seabed, with an earthquake swarm centred on the Explorer Ridge, 240km west of Vancouver Island: the largest quakes have exceeded magnitude 6. In early 2005 extensive seismic swarms were detected around 320km off Vancouver Island: more than 4000 quakes were registered, most small but with some greater than magnitude 4. The tremors occurred in the area known as the Endeavour Ridge, 200km or so south of the Explorer Ridge. Both ridges are characterized by hydrothermal activity, but it is unclear whether the current seismicity is connected in any way to an upsurge in local volcanism. Earthquakes are hardly rare around there anyway, but it’s always worth watching these highly tectonically active parts of the globe.

[Thanks to George Wohanka for information received.]

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British scientists to investigate Caribbean deep-sea hydrothermal vents 10 August 2008

Posted by admin in Caribbean, current research, geoscience, submarine volcanism, volcanology.
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RRS James Cook at the National Oceanography Centre, Southampton (Image credit National Oceanography Centre, Southampton) 

Using the latest in deep-sea exploration technology, British scientists are to investigate the world’s deepest undersea volcanic ridge, 6000 metres down at the bottom of the Cayman Trough in the Caribbean. The United Kingdom’s newest dedicated scientific research vessel, RRS James Cook, will devote two month-long cruises to exploring the Cayman Trough, employing the remotely-operated Isis submarine and the autonomous underwater vehicle Autosub6000.

The scientific team is led by Dr John Copley of the National Oceanography Centre, Southampton, where RRS James Cook is based. The primary focus of the project is the study of the geochemistry and biology of undersea volcanic vents, and the investigation of hydrothermal processes where the Earth’s mantle is directly exposed to seawater. Hydrothermal vents in such cases, says Dr Copley, ‘could be hotter than 500C (930F), and if they are that hot, they will probably have quite different chemistry and life forms – we expect to find new species’.

Image: RRS James Cook at the National Oceanography Centre, Southampton (credit: National Oceanography Centre, Southampton, used with permission).

News
Sub to make deep Caribbean dive – BBC News, 9 August 2008
Robot submarine to dive deep in the Caribbean – ZDNet.com, 10 August 2008

Information
National Oceanography Centre, Southampton – the UK centre for oceanographical research
RRS James Cook – information from the National Oceanography Centre
RRS James Cook Homepage – an unofficial site by a member of the James Cook technical team

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Evidence of explosive volcanism discovered beneath the Arctic Ocean 27 June 2008

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A team of researchers has discovered evidence of explosive volcanism 4km down on the Arctic Ocean seabed, challenging established notions of the nature of volcanic activity at great ocean depths.

The research team, led by scientists from the Woods Hole Oceanographic Institution, found jagged, glassy rock fragments spread out across a 10km2 area around a series of small volcanic cones along the Gakkel Ridge, part of the spreading mid-ocean ridge system beneath the Arctic ice. ‘These are the first pyroclastic deposits we’ve ever found in such deep water, at oppressive pressures that inhibit the formation of steam, and many people thought this was not possible’, said Woods Hole geophysicist Rob Reves-Sohn.

A paper detailing the findings of the Arctic Gakkel Vents Expedition is published in the 26 June 2008 issue of Nature.

Information
Global Volcanism Program: East Gakkel Ridge volcanoes – summary information for the Gakkel Ridge volcanoes, excitingly dubbed ‘unnamed’ by the GVP

News
Under iceScience News, 25 June 2008
Deep-sea volcanism on the Gakkel RidgeNature, 26 June 2008 (editor’s summary)
Geologists discover signs of volcanoes blowing their tops in the deep ocean – Innovations Report, 27 June 2008
Fire under the ice – EurekAlert, 27 June 2008

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Icelandic submarine volcano: National Geographic News reports 23 April 2008

Posted by admin in current research, Iceland, submarine volcanism, volcanology.
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National Geographic News has an article today about the submarine volcano recently discovered off the south-west of Iceland by University of Iceland volcanologist Ármann Höskuldsson:

The structure turned out to be an active volcano that rises about 3,300 feet (1,000 meters) above the surrounding sections of the ridge, coming within 1,300 feet (400 meters) of the surface. At its base the volcano is approximately 30 miles (50 kilometers) across. The peak contains a depression known as a caldera that is 6 miles (10 kilometers) wide.

The size of the edifice, says Höskuldsson, indicates that it is being fed by its own magma chamber. Next year he and his team are planning to use a submarine to explore the volcano, hoping to clarify the anomaly of why it has developed in a region where tectonic plates pulling apart normally prevent the growth of such large volcanic structures.

Information
Smithsonian Institution Global Volcanism Program – volcanoes of Iceland and the Arctic Ocean
Volcanoes in Iceland – University of Iceland Institute of Earth Sciences

News
Giant undersea volcano found off IcelandNational Geographic News, 22 April 2008

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Icelandic submarine volcano ‘simmers sinisterly’ 12 April 2008

Posted by admin in current research, Iceland, submarine volcanism, volcanology.
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English-language Icelandic news website Iceland Review Online has another report on the large submarine volcano identified by Ármann Höskuldsson off the Reykjanes peninsula in southwest Iceland, written in what’s perhaps best described as an informal, lively style:

Bubbling hot underneath 1,500 meters of water, a volcanic caldera (the lava spitting mouth of a volcano) measuring 10 kilometers in diameter simmers sinisterly. Scratching their heads, a group of Icelandic scientists wonder how it got there in the first place.

Taking a few minutes off from scratching his head, Höskuldsson warns that ‘People shouldn’t be surprised if there would be an extensive volcanic eruption underwater there soon. Nothing has happened for hundreds of years and it is in fact only a matter of time before there will be an eruption’.

Information
Smithsonian Institution Global Volcanism Program – volcanoes of Iceland and the Arctic Ocean
Volcanoes in Iceland – University of Iceland Institute of Earth Sciences

News
A volcanic surprise – Iceland Review Online, 12 April 2008

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Submarine volcano discovered off Iceland: report 8 April 2008

Posted by admin in current research, Iceland, submarine volcanism, volcanology.
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Iceland Review Online reports today that a large submarine volcano has been found off the Reykjanes peninsula in southwest Iceland.

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. In the center of the volcano there is a caldera measuring ten kilometers in diameter.

The presence of such a large caldera volcano in an area of ocean ridge volcanism is ‘a surprise’. The volcano reported here is presumably part of the Reykjaneshryggur submarine volcanic system, although the article doesn’t say so.

Höskuldsson and his team will be presenting a paper on their discovery at the IAVCEI 2008 general assembly to be held in Reykjavík in August.

Information
Smithsonian Institution Global Volcanism Program – volcanoes of Iceland and the Arctic Ocean
Volcanoes in Iceland – University of Iceland Institute of Earth Sciences

News
Giant underwater volcano discovered in Iceland – Iceland Review Online, 8 April 2008

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