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Volcanic Advisory 6

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Summary
The volcanic eruption between Hunga Tonga and Hunga Ha’apai, 65 km from Nuku'alofa has ceased.

The new volcano in the Hunga Tonga-Hunga Ha’apai region, 65km from Nuku’alofa North west of Nuku’alofa was visited for the 3rd time on January 24 on board the VOEA Neiafu.
The eruption from the new island that started growing over a month ago appears to be over. There were no sign of any emissions of ash, gas or steam observed coming out from the vent of the new formed island.

There were no trace of rafts of pumice or other floating volcanic debris observed. No smells of volcanic gases were noticed within 100m of the island. Hunga Tonga (200m to the north of the new island) and Hunga Ha’apai islands (joined to the west) were covered by dark coloured ash from the eruption over the last month, but now turned into lighter colour due to oxidation of iron and aluminum elements.

Introduction
This is the sixth advisory of the volcanic activity in the Hunga Tonga – Hunga Ha’apai region. The advisories had been based on collective information provided by Tonga Broadcasting Commission, Tonga Meteorological Services, Tonga Airport Limited, Real Tonga Airlines, Volcanic Ash Advisory Centre (VAAC, Wellington), GNS-NZ, His Majesty’s Armed Force, National Emergency Management Office, Lands & Survey Department and Tonga Volcano Advisory Centre. The content of this edition is largely based on the site expedition conducted on the 24th January 2015 sponsored by the New Zealand High Commission.

New Island Location
A new island was formed during the eruption that started on the 19th December 2014 is located between Hunga Tonga and Hunga Ha’apai (Figure 1). The new island is about 120m high, 1.5km wide (NS) and 2.0km (WE). It is joined with Hunga Ha’apai to the west and about 150 – 200 meters short to Hunga Tonga.
All three islands were covered by dark colored ash from the eruption. The sediments have changed into lighter colors due to oxidation is iron (Fe) and aluminum (Al) elements within the material (Fig. 2 & 3). Further investigations is needed to determine the physicality of the island

Figure 1. Location map showing the new island formed between Hunga Ha'apai and Hunga Tonga, 65 km north-west of Nuku'alofa. The island (marked yellow) is over 1 km in diameter. The crater (marked red) is estimated 400-500m.

Island Observations
There were attempt to land on the new island but due to the large swells made it difficult.

Figure 2. Westward view of the island (Hunga Ha’apai to the left). The island is estimated to be 1.5km NE wide and 2km WE long (Taken 24-Jan-15). The crater is apparent to the east being the deeper end of the area, and the volcanic debris are deposited at depth allowing the shallower west end to accumulate upwards faster, emerging higher above sea level.

Figure 3. Southward view of the island, Hunga Ha’apai on the right and Hunga Tonga on the left. The island is joined with Hunga Ha’apai to the west. The peak height on Hunga Ha’apai is 120m above sea level. (Taken 24-Jan-15).

Figure 4. Westward view of the join between Hunga Ha’apai (left) and the west end of the new island taken 100m from shore. (Taken 24-Jan-15).

Figure 5. Westward close up view of the new island crater taken 100m away. Note the color of the material is lighter than it was in the last visit (7 days before) due to oxidation of the elements such as iron (Fe) and aluminum (Al) (Taken 24-Jan-15).

Conclusion
The eruption that formed the new island between Hunga Tonga and Hunga Ha’apai over a month ago appears to be over. Monitoring will be on going.

The next advisory will be issued when more information becomes available.

Contact and Further Information
For further information contact the National Volcano Advisory Center of the Ministry of Lands and Natural Resources at Telephone 25508 or Email: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

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