Report on White Island (New Zealand) — January 1981
Scientific Event Alert Network Bulletin, vol. 6, no. 1 (January 1981)
Managing Editor: Lindsay McClelland.
White Island (New Zealand) Ash, impact craters, gas clouds, seismicity
Please cite this report as:
Global Volcanism Program, 1981. Report on White Island (New Zealand). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 6:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198101-241040.
37.52°S, 177.18°E; summit elev. 321 m
All times are local (unless otherwise noted)
NZGS personnel flew over White Island on the morning of 6 January. In the 10 minutes they were over the island, the voluminous convoluting emissions of white steam and gas clouds obscured their view around and into 1978 Crater. The lower portion of the 600-750-m-high eruption column was slightly ash-charged. The main crater was thickly covered with eroded brown-green ash. Impact craters extended a few hundred meters NE from 1978 Crater. Conspicuous blue fumes were associated with the steam-gas column rising in the 1914 landslide area just SE of 1978 Crater.
Seismicity since ground inspections in early December was characterized by four distinct periods of marked increase. Intervals of high-frequency, high-amplitude tremor were recorded for 32 hours on 15-16 December, for 35 hours on 22-23 December, and for 26 hours on 27-28 December. Strong ash emissions were likely during these periods. Large discrete earthquakes were recorded on 14 December and 2 January.
Geologic Background. Uninhabited 2 x 2.4 km White Island, one of New Zealand's most active volcanoes, is the 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 summit crater appears to be breached to the SE, because the shoreline corresponds to the level of several notches in the SE crater wall. Volckner Rocks, four sea stacks that are remnants of a lava dome, lie 5 km NNE. Intermittent moderate phreatomagmatic and strombolian eruptions have occurred throughout the short historical period beginning in 1826, but its activity also forms a prominent part of Maori legends. Formation of many new vents during the 19th and 20th centuries has produced 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.
Information Contacts: B. Scott, NZGS, Rotorua.