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2012 Kermadec Islands eruption

Major undersea volcanic eruption in the Kermadec Islands of New Zealand

Field	Value
name	2012 Kermadec Islands eruption
photo	File:Havre Seamount Eruption 19 July 2012 with labels.jpg
photo-size	200px
caption	NASA image of Havre Seamount eruption and initial formation of pumice raft
start_date	18 July 2012
start_time	Morning
end_date	19 July 2012
volcano	Havre Seamount
type	Submarine
location	Kermadec Islands
coordinates
VEI	1

|photo-size = 200px |map-size = |map-caption =

The 2012 Kermadec Islands eruption was a major undersea volcanic eruption that was produced by the previously little-known Havre Seamount near the L'Esperance and L'Havre Rocks in the Kermadec Islands of New Zealand. The large volume of low density pumice produced by the eruption accumulated as a large area of floating pumice, a pumice raft, that was originally covering a surface of 400 km², spread to a continuous float of between 7500 and and within three months dispersed to an area of more than twice the size of New Zealand.

The thickness of the raft may initially have been as high as 3.5 m and was reduced to around 50 cm within a month.

Three months after the eruption, the mass had dispersed into very dilute rafts and ribbons of floating pumice clasts. Most pumice clasts became waterlogged and sank to the sea floor, while some flocks have stranded in the Tonga islands, on the northern shores of New Zealand, and eventually on the eastern coast of Australia one year after the eruption.

While the eruption is officially rated as a VEI-1 by the Smithsonian Institution, studies have found that approximately 1.5 cubic kilometres of material erupted, which correlates to a VEI-5 eruption.

Eruption

Bathymetric map of Kermadec islands and seamounts

The eruption of the Havre Seamount was not initially noticed by scientists, and volcanologists were not even aware that the Havre Seamount was an active submarine volcano. These earthquakes were consistent with magma rising into a magma chamber prior to eruption.

In 2015 a scientific expedition set out to study changes of seafloor topography in the area surrounding Havre Seamount. The same group of researchers mapped the distribution of the floating pumice blocks driven by wind, ocean currents and eddies.

Pumice raft

Scientists were not aware that any eruption had occurred until a huge pumice raft was sighted and photographed at 14:40 NZST on 31 July 2012 by Maggie de Grauw while on a commercial flight from Faleolo, Samoa to Auckland, New Zealand. She emailed her pictures to Dr Scott Bryan, senior research fellow at Queensland University of Technology. After discussion, it was ascertained that the raft was around 1000 km north of Auckland. Bryan then contacted Olivier Hyvernaud from the Laboratoire de Géophysique, Tahiti, who confirmed the location from Terra/MODIS imagery from NASA. The raft was subsequently sighted by members of the New Zealand Defence Force on 9 August 2012—several weeks after the eruption had occurred. It was spotted by an Orion aircraft and then approached and sampled by the strategic sealift ship HMNZS Canterbury. The pumice raft measured approximately 300 mi in length and more than 30 mi in width, making the floating island larger in surface area than Israel. An officer in the Royal Australian Navy said that it was "the weirdest thing [he had] seen in 18 years at sea".

References

[http://ars.sciencedirect.com/content/image/1-s2.0-S0377027306001181-gr2.jpg Science Direct map of Kermadec Islands and Seamounts] {{webarchive. link. (2 February 2013)
Klemetti, Erik. (13 August 2012). "Havre Seamount: The Source of Kermadec Island Pumice Raft?". Wired.
Bryner, Jeanna. (14 August 2012). "'Raft' in Pacific Found, NASA Says". [[Live Science]].
Memmott, Mark. (10 August 2012). "7,500 Square Miles of Pumice Floating in Pacific Is 'Weirdest Thing I've Seen'". [[NPR]].
(10 August 2012). "Massive Rock Raft Found Floating off New Zealand". [[ABC News (United States).
[http://web.whoi.edu/mesh/ Website] of the expedition ''Mesh''
(22 April 2014). "On the fate of pumice rafts formed during the 2012 Havre submarine eruption". [[Nature Communications]].
(2018-01-05). "The largest deep-ocean silicic volcanic eruption of the past century". [[Science Advances]].
Cooke, Michelle. (11 August 2012). "Scientists rock theory on pumice raft". [[Stuff.co.nz]].
Gannon, Megan. (13 August 2012). "Mystery Rock Shelf Floating in Pacific: Floating pumice rocks are covering an area larger than Israel in the South Pacific.". [[Discovery News]].

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

submarine-eruptions 21st-century-volcanic-events geography-of-the-new-zealand-seabed seamounts-of-the-pacific-ocean kermadec-islands floating-islands 2012-in-new-zealand history-of-the-new-zealand-outlying-islands vei-1-eruptions volcanic-eruptions-in-new-zealand

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