Report on Hunga Tonga-Hunga Ha'apai (Tonga) — May 1988

Scientific Event Alert Network Bulletin, vol. 13, no. 5 (May 1988)
Managing Editor: Lindsay McClelland.

Hunga Tonga-Hunga Ha'apai (Tonga) Lava and tephra from shallow submarine site

Please cite this report as:

Global Volcanism Program, 1988. Report on Hunga Tonga-Hunga Ha'apai (Tonga). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 13:5. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198805-243040.

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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)


Fishermen reported the beginning of an eruption E of Hunga Ha'apai Island on 1 June at 0800. They noted the ejection of "fire," tephra, and large volumes of dense white smoke/steam. Sea water nearby was warm. The next day, a Friendly Islands Airways pilot reported an active eruption at the S edge of a shoal. Vigorous steam emission was occasionally punctuated by ejection of solid material. On 3 June at 0915, a Friendly Islands flight with geologists Saimone Helu (Ministry of Lands, Tonga), Julian Pearce, and Michelle Ernewein (Newcastle Univ) was diverted to view the eruption. The eruption was continuing in shallow water ~1 km SSE of Hunga Ha'apai. Lava had apparently been erupted from three sources in a SW-NE trend extending 100-200 m, with current activity at the SW end. There was no evidence of a new island.

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.

Information Contacts: R. Gatliff, S. Helu, and S. Tongilava, Ministry of Lands, Survey, and Natural Resources, Tonga; R. Singh, Mineral Resources Dept, Suva, Fiji.