Showing posts with label Kermadec Ridge. Show all posts
Showing posts with label Kermadec Ridge. Show all posts

Saturday, 24 September 2022

Warnings issued to mariners and aviators after Home Reef Volcano, Tonga, erupts eight times in forty eight hours.

Warnings have been issued to air and sea traffic after Home Reef Volcano, an ephemeral island volcano in Tonga, erupted eight times in a 48 hour period between 18 and 20 September 2022. Aviators have been warned not to approach within three kilometres of the volcano, due to the dangers of volcanic ash to aircraft engines, and mariners have been advised not to approach the volcano and to be vigilant for rafts of floating pumice (volcanic rock with numerous large pore-spaces which can float on water), which can be damaging to boats.

Image of an eruption on Home Reef captured by the Operational Land Imager-2 instrument on the Landsat-9 satellite on 14 September 2022. NASA/Earth Observatory.

Home Reef is usually beneath the water, but the formation of temporary islands from ash effusions which are subsequently washed away has previously recorded in 1852, 1857, 1984 and 2006. The volcano began to erupt again on 10 September 2022, and by 17 September had formed an island with an area of 24 300 m², which by 23 September had grown to 32 375 m².

Home Reef lies on the Tonga/Kermadec Ridge, and is fed by the subduction of the Pacific Plate beneath the Australian Plate along the Kermadec/Tonga Trench. As the Pacific Plate sinks into the Earth, it is warmed by the heat from the planets interior. This leads to partial melting of the Pacific Plate, with some of the melted material rising through the overlying Australian Plate as magma, fuelling the volcanos of the Kermadec/Tonga Ridge.

Diagram showing subduction along the Tonga Trench, and how this feeds the volcanoes of the Tonga Volcanic Arc. York University.

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Saturday, 15 January 2022

Tsunami warning issued across the Kingdom of Tonga following an eruption on the Hunga Ha'apai underwater volcano.

A tsunami warning was issued to people living in coastal areas on all the islands of the Kingdom of Tonga on Thursday 13 January 2022, following an eruption on the Hunga Ha'apai underwater volcano, which produced a column of gas and ash about 20 km high. In the event, the largest wave observed was only about 30 cm high, which reached Nuku'alofa on the north coast of the island of Tongatapu at about 12.30 pm local time. The volcano began its current eruptive cycle on 20 December 2021, prior to which it had been inactive since 2015.

 
GOES-17 satellite imigary of the 13 January 2022 Hunga Ha'apai underwater volcano eruption. University of Wisconsin Madison/Space Science and Engineering Center/CIMMS Satelite Blog.

Hunga Ha’apai lies on the Tonga/Kermadec Ridge, and is fed by the subduction of the Pacific Plate beneath the Australian Plate along the Kermadec/Tonga Trench. As the Pacific Plate sinks into the Earth, it is warmed by the heat from the planets interior. This leads to partial melting of the Pacific Plate, with some of the melted material rising through the overlying Australian Plate as magma, fuelling the volcanos of the Kermadec/Tonga Ridge.

 
Diagram showing subduction along the Tonga Trench, and how this feeds the volcanoes of the Tonga Volcanic Arc. York University.

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Wednesday, 22 December 2021

Eruption on Hunga Ha'apai volcano, Tongo.

The remote Hunga Ha'apai volcano in Tongo erupted on Monday 20 December 2021, producing an ash column 18 km high, and ash-falls across the island group. There are no reports of any casualties associated with this event, however, local authorities are warning people not to collect rainwater for drinking (a common practice in a nation where many communities do not have access to other water sources) until the ash cloud has cleared, due to the dangers of acid rain, which can cause severe health problems. Aircraft were warned to keep away from the islands during the eruption, resulting in the cancellation of at least one flight.

 
An eruption on the Hunga Ha'apai volcano, seen from Nuku'alofa on Monday 20 December 2021. Mary Lyn Fonua/AFP.

Hunga Ha’apai lies on the Tonga/Kermadec Ridge, and is fed by the subduction of the Pacific Plate beneath the Australian Plate along the Kermadec/Tonga Trench. As the Pacific Plate sinks into the Earth, it is warmed by the heat from the planets interior. This leads to partial melting of the Pacific Plate, with some of the melted material rising through the overlying Australian Plate as magma, fuelling the volcanos of the Kermadec/Tonga Ridge.
 
 
Diagram showing subduction along the Tonga Trench, and how this feeds the volcanoes of the Tonga Volcanic Arc. York University.
 
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