Report on White Island (New Zealand) — November 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 11 (November 1991)
Managing Editor: Lindsay McClelland.
White Island (New Zealand) Tephra emission continues from new crater
Please cite this report as:
Global Volcanism Program, 1991. Report on White Island (New Zealand). In: McClelland, L. (ed.), Bulletin of the Global Volcanism Network, 16:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199111-241040.
37.52°S, 177.18°E; summit elev. 321 m
All times are local (unless otherwise noted)
An explosive episode on 24 November at 1400 ejected a tephra column and produced an E-type seismic event detected by a nearby seismometer. The tephra column was seen from the mainland by helicopter pilot R. Fleming, who estimated that it rose to 2,000 m.
Fieldwork on 28 November revealed fresh andesitic scoria bombs scattered over a wide area from 250 m NE to 500 m ESE of its probable source, the new crater (Wade) that had formed in mid-October (BGVN 16:10). Bombs ranged to 50 cm across and most were irregularly shaped. As much as 2 cm of gray ash covered the brick-red ash erupted by the new crater in late October and early November. During the 2-hour visit, emission of gas and fine, gray-brown ash from Wade crater was essentially continuous, accompanied by constant loud rumbling and occasional clattering noises that were probably caused by rocks striking the vent walls. The new crater was much larger than when first seen on 23 October, forming an oval to sub-rectangular slot extending across the floor of the 1978/91 Crater complex. TV1 crater, roughly 100 m NE of Wade, weakly emitted vapor and fine gray ash. May 91 crater appeared quiet.
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: C. Wood, DSIR Geology & Geophysics, Rotorua.