Report on Hunga Tonga-Hunga Ha'apai (Tonga) — 31 December-6 January 2015

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 December-6 January 2015
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2014. Report on Hunga Tonga-Hunga Ha'apai (Tonga). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 31 December-6 January 2015. Smithsonian Institution and US Geological Survey.

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Hunga Tonga-Hunga Ha'apai

Tonga

20.536°S, 175.382°W; summit elev. 114 m

All times are local (unless otherwise noted)


Based on a pilot observation, the Wellington VAAC reported that an ash plume from Hunga Tonga-Hunga Ha'apai rose to an altitude of 3 km (10,000 ft) a.s.l. on 6 January.

Geologic Background. The small islands of Hunga Tonga and Hunga Ha'apai cap a large seamount located about 30 km SSE of Falcon Island. The two linear andesitic islands are about 2 km long and represent the western and northern remnants of the rim of a largely submarine caldera lying east and south of the islands. Hunga Tonga reaches an elevation of about 114 m above sea level, and both islands display inward-facing sea cliffs with lava and tephra layers dipping gently away from the submarine caldera. A rocky shoal 3.2 km SE of Hunga Ha'apai and 3 km south of Hunga Tonga marks a historically active vent. Several submarine eruptions have occurred at Hunga Tonga-Hunga Ha'apai since the first historical eruption in 1912. An eruption that began in mid-December 2014 built a new island between the other two large islands.

Source: Wellington Volcanic Ash Advisory Center (VAAC)