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Scientists return to active undersea volcano 20 March 2009

Posted by admin in current research, geoscience, Pacific, submarine volcanism.
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In 2004 an international team of scientists using a remotely-operated submersible witnessed an undersea volcanic eruption for the first time at Northwest Rota-1, a seamount rising to 517 metres below the sea surface in the Mariana Islands. Further scientific studies were carried out at the site in 2005 and 2006. Last year hydrophones recorded sounds of eruptive activity at the site.

In April this year the scientific team will be returning to Northwest Rota-1 for further studies, says a press release from Oregon State University:

During the two-week project, the scientists will deploy long-term monitoring instruments including hydrophones, chemical sensors, current meters and plume sensing devices that will allow them to study for the first time the patterns of activity over an entire year. They also will make additional visual observations of the eruptive activity, hydrothermal vents and biological communities, and will collect samples of lava, gas and fluids from the volcano.

It will be fascinating to see what they come up with. The NOAA website for the April 2009 cruise can be found here: Vents Program: Marianas.

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Hunga Tonga-Hunga Ha’apai update, 20 March 2009 20 March 2009

Posted by admin in activity reports, eruptions, Pacific, submarine volcanism, Tonga.
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Tonga submarine eruption, 20 March 2009 0130GMT (NASA Aqua image)
Above: MODIS image from NASA Aqua satellite captured at 01:30 GMT on 20 March 2009. The island of Tongatapu is at the lower edge of the image. The site of the eruption is marked by the yellow arrow: a small plume can be seen extending ENE, and floating ash is staining the sea around the volcano greenish-blue. [source]

Eruptive activity at Hunga Tonga-Hunga Ha’apai appears to have declined somewhat over the last 12 hours, according to the latest advisory from Wellington VAAC (10:29 GMT 19 March 2009). The VAAC advisory, based on pilot observations and satellite imagery, reports ‘no more active eruptions, steaming to 6000ft [1800 metres]’, with ‘white and wispy ash haze extending to large areas ENE blw 5000ft [below 1500 metres]’. An earlier advisory (17:58 GMT 19 March 2009) reported frequent eruptions and ash clouds to FL130 (13000 feet, 4000 metres), with a plume extending 300 miles (480 kilometres) ENE.

At 01:30 GMT today NASA’s Aqua satellite captured a MODIS image which showed only a small plume extending less than 10 kilometres ENE of the volcano (from the NASA MODIS Rapid Response site: original image is here, detail reproduced above).

The BBC has some fresh video of the eruption from the inspection trip made by Tongan geologists yesterday. CBS News has the AP report of the eruption, with added video, pictures, and the usual mad/dumb/hilarious comments from the visiting public; they also have a short photo essay on the eruption (titled, in typically odd CBS fashion, ‘Undersea Volcano Erupts Photos’). And the Boston Globe’s ‘Big Picture’ feature lives up to its name with spectacular big, big pictures of the eruption.

As if this eruption wasn’t enough of a reminder that Tonga is situated in a geologically highly active part of the planet, there was a magnitude 7.9 earthquake in the Tongan Arc yesterday. There is no reason to suspect a direct link to the eruption. A tsunami alert was issued following the earthquake, but was later cancelled because it was ‘a tiny tsunami … nothing to worry about’.

UPDATE: Lousy science reporting from the BBC, who are asserting on the basis of no evidence at all that ‘An earthquake may have triggered an underwater volcano to erupt’. Nice video, clueless commentary: Quake may have caused eruption. Additional update, Dr Klemetti at Eruptions is also irritated by this stuff: ‘absolutely terrible “science” journalism … silly note of dread … all conjecture’.

For all our coverage of the Tonga eruption: Tonga « The Volcanism Blog.

News
Undersea volcano making waves in the Pacific – CBS News, 19 March 2009
Volcano shatters Pacific calm around TongaThe Independent, 20 March 2009
South Pacific volcano inspected – BBC News, 20 March 2009

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

The Volcanism Blog

More on Hunga Tonga-Hunga Ha’apai 19 March 2009

Posted by admin in eruptions, Pacific, submarine volcanism, Tonga.
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The eruption is ongoing at Hunga Tonga-Hunga Ha’apai: the latest volcanic ash advisory from Wellington VAAC, issued at 05:23GMT today, reports ash emissions at FL130 (13000 feet or about 4000 metres), expected to rise to FL150 (15000 feet or about 4500 metres) over the next few hours. The Aviation Herald quotes Airways New Zealand reports of ash up to 15km, but VAAC statements give no confirmation of this figure.

The Aqua MODIS image of the Hunga Tonga-Hunga Ha’apai eruption that we were able to preview on this blog yesterday (thanks to our friends at NASA) is now available at the NASA Earth Observatory, in the ‘natural hazards’ category: Submarine Eruption in the Tonga Islands (18 March 2009). The image comes with the usual annotations and detailed commentary.

BBC News has a video of the eruption (some stills from the same video can be found at our earlier post) which is a beautiful case study in hydrovolcanic phenomena: voluminous steam clouds, violent explosive activity, dark and rapidly expanding eruptions of volcanic ejecta, debris clouds spreading across the ocean. Spectacular stuff. The video also shows clearly that there are currently two active vents.

Associated Press reports Tongan authorities saying that ‘there have been no reports of fish or other animals being affected’. This seems on the face of it unlikely, and is contradicted by other reports. A TVNZ report on the eruption says that ‘Boaties who were close by when the eruption took place talked of burning birds falling from the sky’ and that ‘wildlife from the island closest to the eruption have been completely destroyed’, while ABC Radio Australia quotes a Tongan journalist: ‘There were lots of dead fishes and dead birds’.

Tongan government geologists will be making an inspection of the area by boat today. They couldn’t go earlier, as no-one could agree who should pay the Tongan Navy for the fuel the trip would use.

For all our coverage of the Tonga eruption: Tonga « The Volcanism Blog.

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
Underwater volcano erupts off Tonga – BBC News, 19 March 2009
Underwater volcano sends huge columns of ash into Pacific skyThe Times, 19 March 2009
Underwater volcano continues erupting – TVNZ, 19 March 2009
Tongan inspection team heads to undersea volcano – Associated Press, 19 March 2009
Tonga officials inspect volcano’s environmental impact – ABC News, 19 March 2009
Tonga undersea volcano hampers Pacific air trafficAviation Herald, 19 March 2009
Undersea volcano erupts off Tonga – Press Association, 19 March 2009
Geologists inspect underwater volcano site off Tonga – ABC Radio Australia, 19 March 2009
Visual checks to be made of underwater volcano – Radio New Zealand, 19 March 2009

The Volcanism Blog

Hunga Tonga-Hunga Ha’apai eruption images 19 March 2009

Posted by admin in eruptions, Pacific, submarine volcanism, Tonga.
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A Japanese reader of The Volcanism Blog has sent in the following images of the Hunga Tonga-Hunga Ha’apai eruption, captured from a video taken on 18 March 2009.

Hunga Tonga-Hunga Ha'apai eruption, 18 March 2009

Hunga Tonga-Hunga Ha'apai eruption, 18 March 2009

Hunga Tonga-Hunga Ha'apai eruption, 18 March 2009

Hunga Tonga-Hunga Ha'apai eruption, 18 March 2009

Hunga Tonga-Hunga Ha'apai eruption, 18 March 2009

Hunga Tonga-Hunga Ha'apai eruption, 18 March 2009

These images clearly show that there are two active vents. The white plume consists mainly of steam, the dark masses are dark pyroclastic material projected violently upwards as water enters the magmatic vents, creating powerful phreatic explosions. The ragged-edged effect visible on the dark clouds is caused by larger fragments of ejected material following parabolic curves as they are hurled upwards and outwards, trailing smaller fragments behind them.

UPDATE: The video from which these images are clearly taken has turned up on the BBC News website: Underwater volcano erupts off Tonga. At the end of the video, around the point from which the final image reproduced above comes, voices can be heard off-camera saying ‘I think we should run away’, and ‘turn the boat around’.

For all our coverage of the Tonga eruption: Tonga « The Volcanism Blog.

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

The Volcanism Blog