Report on Whakaari/White Island (New Zealand) — September 1992
Bulletin of the Global Volcanism Network, vol. 17, no. 9 (September 1992)
Managing Editor: Lindsay McClelland.
Whakaari/White Island (New Zealand) Block ejection enlarges active crater
Please cite this report as:
Global Volcanism Program, 1992. Report on Whakaari/White Island (New Zealand) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 17:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199209-241040.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
A new impact-crater field, extending to roughly 350 m ESE from the rim of the 1978/92 crater complex, was seen by helicopter pilot R.Fleming on 28 June. Morphology of the impact craters suggested that they were only a few days old, and that many of the ballistic blocks that had produced the craters had near-vertical trajectories. The eruption apparently occurred from the W part of the 1978/92 complex, substantially enlarging Wade Crater ... . NE of the 1978/92 complex, the wall separating the April 91 pit from Donald Duck Crater had been removed by the end of June, perhaps 1-2 weeks earlier.
None of the activity was witnessed, but seismic data suggest the possible timing. June-August volcanic seismicity was generally at low levels, with 2-5 A-type shocks/day. Geologists suspect that the wall dividing April 91 and Donald Duck craters collapsed on 17-18 June, when 17 A-type events were recorded daily. Wade Crater's eruption may have accompanied 13 E-type (explosion) events recorded 23-24 June, or it may have been triggered by a ML 5.6 tectonic earthquake on 21 June, centered ~20 km SW of White Island. Numerous aftershocks followed: 200 on 22 June, 150 on the 23rd, 40 on the 24th, and 10-20/day for the next 5 days. B-type events typically occurred at rates of 1-3 every other day, and there was no significant volcanic tremor.
Fieldwork by B. Scott on 2 September revealed that Wade Crater had enlarged substantially since May, and had developed 3 sub-craters. A western sub-crater, separated by a wall 15-20 m high, extended Wade 50-80 m W from its former rim. A bright-green crater lake filled the central portion, and a hummocky eastern section continued to erode until only narrow walls remained between it and two other steaming vents (May 91 and TV1). A pit dug just outside the SE rim of the 1978/92 complex showed an accumulation of ~55 mm of ash since May.
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: B. Scott, Institute of Geological and Nuclear Sciences (IGNS), Rotorua [formerly DSIR].