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Report on Whakaari/White Island (New Zealand) — May 1980

Whakaari/White Island

Scientific Event Alert Network Bulletin, vol. 5, no. 5 (May 1980)
Managing Editor: David Squires.

Whakaari/White Island (New Zealand) Explosions continue; new fumaroles and renewed inflation

Please cite this report as:

Global Volcanism Program, 1980. Report on Whakaari/White Island (New Zealand) (Squires, D., ed.). Scientific Event Alert Network Bulletin, 5:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198005-241040

Whakaari/White Island

New Zealand

37.52°S, 177.18°E; summit elev. 294 m

All times are local (unless otherwise noted)

Geologists visited White Island on 26 May. During the first half of the 5-hour visit, eruptive activity was limited to emission of a white vapor column. After ash darkened the vapor column briefly, a small explosion ejected accessory blocks to a few tens of meters above the rim of 1978 Crater. A vigorously convecting gas and ash column deposited ash and lapilli-sized accessory material around the crater. Acidic, ash-charged water droplets fell within 400 m of the crater. A smaller explosion occurred about 40 minutes later. Both explosions were recorded by the White Island seismograph, which had recorded two similar but much larger events during the 2 previous days. One of the earlier explosions was observed from near Motiti Island, ~70 km away.

Since the previous ground inspection on 18 April, a line of 3 new fumaroles had formed NE of 1978 Crater, along a trend of pre-existing intense fumarolic activity. Temperatures in the new fumaroles ranged from 475 to 615°C. The largest vent, 10 m in diameter and 15 m deep, was surrounded by two small lobes of ejecta. Fumarolic activity elsewhere on the main crater floor had become substantially stronger, and several other new gas vents were observed. Divers found warm springs just off the NE and NW coasts of White Island, measuring a temperature of 45°C at a depth of 0.3 m at one of the sites.

A levelling survey revealed much more extensive and rapid uplift in the main crater since 18 April than had occurred in the 5 previous months. The maximum inflation values of 22-27 mm were measured in the portion of the survey area nearest 1978 Crater and the zone of intense fumarolic activity mentioned above. The inflation recorded since November 1979 was a reversal of steady deflation between February 1978 and August 1979. A magnetic survey of the main crater yielded no significant changes since 18 April. A pit dug about 200 m E of 1978 Crater went through 270 mm of tephra before reaching August 1979 deposits. Very little tephra had accumulated more than 400 m from 1978 Crater since August 1979.

Geological Summary. The uninhabited Whakaari/White Island is the 2 x 2.4 km emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater is open at sea level, with the recent activity centered about 1 km from the shore close to the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. The formation of many new vents during the 19th and 20th centuries caused rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project. Explosive activity in December 2019 took place while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Maori name of Te Puia o Whakaari ("The Dramatic Volcano") and White Island (referencing the constant steam plume) given by Captain James Cook in 1769.

Information Contacts: B. Houghton, E. Lloyd, and I. Nairn, NZGS, Rotorua; R. Dibble, Victoria Univ., Wellington.