Report on Whakaari/White Island (New Zealand) — March 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 3 (March 1987)
Managing Editor: Lindsay McClelland.
Whakaari/White Island (New Zealand) Continued ash emission
Please cite this report as:
Global Volcanism Program, 1987. Report on Whakaari/White Island (New Zealand) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 12:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198703-241040.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
Several ash eruptions have occurred since geologists visited the crater on 3 February. Emissions occurred both before and after the M 6.3 earthquake on 2 March, and heavy steaming was observed on 3 March.
When geologists returned on 28 March, new ash covered at least the E half of the island to a maximum measured thickness of 20 cm, burying the 25 January block deposit E of 1978 Crater. Ash was predominantly lithic with a minor fresh magmatic component. Congress Vent had enlarged 2-3 times in diameter and expanded W across the floor of 1978 Crater, forming a vertical-walled, flat-floored, circular shaft ~50 m deep. On 28 March, ash and high-pressure gas emission was occurring from a several-meter-wide, sub-horizontal, pipe-like opening in the NW wall. The pipe remained incandescent red during an hour of observation. Temperatures of two fumaroles E of 1978 Crater were measured on 28 March: one had decreased from 343 to 180°C since 3 February and the second had increased from 244 to 280°C.
Significant tremor was recorded on the White Island seismograph 17 February-11 March and 21-22 March. Small to moderate low-frequency volcanic earthquakes (B-type) dominated activity during periods without tremor. A few high-frequency volcano-tectonic events accompanied the B-type events. Small earthquakes, possibly eruption (E-type) were recorded on 20 February, and 23, 26, and 27 March. On 28 March a small E-type earthquake that was followed by 10 minutes of low-amplitude tremor was associated with a moderate ash eruption between 1000 and 1020 during the geologists' visit.
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, NZGS Rotorua.