Report on Whakaari/White Island (New Zealand) — July 1982
Scientific Event Alert Network Bulletin, vol. 7, no. 7 (July 1982)
Managing Editor: Lindsay McClelland.
Whakaari/White Island (New Zealand) Eruption column and seismicity; new crater
Please cite this report as:
Global Volcanism Program, 1982. Report on Whakaari/White Island (New Zealand) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 7:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198207-241040.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
On 1 July at 1413 a wide-band earthquake sequence indicative of an eruption was recorded, with peak-to-peak amplitude exceeding Full-Scale Deflection (FSD). From Whakatane, S. Harvey reported that a dark eruption column and ash fallout accompanied the earthquakes. Harvey observed an eruption column until 1517, by which time the seismicity had declined to 2-3 mm peak-to-peak, low-frequency, tremor-like activity. Two smaller wide-band earthquake sequences were recorded on 3 July at 0234 and 5 July at 0424.
About noon on 8 July NZGS personnel flew over the volcano. There was no sign of any new ash deposition or impact craters. A steam plume was rising to about 900 m from the SE part of 1978 Crater, and much smaller steam plumes were being emitted from the fumarole area in the center of the main crater. Emission was more intense than during the 1 June visit and during a photographic flight on 13 June. The green lake observed in the SE part of 1978 Crater during several previous visits was still present.
A sharp-walled pit had formed in the N part of 1978 Crater. It was filled with steam and opened into the gully that drains into the SE part. It had not been seen on March airphotos, but a small depression was noted in this area on 13 June photographs.
Between 2 June and 5 July the daily number of low-frequency (B-type) seismic events declined. Only on 24, 28 and 30 June were there more than 20 (maximum of 37 on 28 June), as compared to 27 February-2 June when the number of events often exceeded 150 per day. All were very small.
High-frequency (volcano-tectonic) seismic events numbered fewer than 3/day after 2 June. All events were small except on 2 July at 2027 when they exceeded FSD. On 21-22 June, 4 medium-frequency volcanic earthquakes were recorded. NZGS personnel interpret these as possible intrusive events. Tremor-like seismic activity was recorded 18-19 and 30 June, and 2, 3, and 4 July.
Geologic Background. 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: I. Nairn and B. Scott, NZGS, Rotorua; P. Otway, NZGS, Wairakei.