Report on Whakaari/White Island (New Zealand) — March 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 3 (March 1991)
Managing Editor: Lindsay McClelland.
Whakaari/White Island (New Zealand) Ash emission from new vent
Please cite this report as:
Global Volcanism Program, 1991. Report on Whakaari/White Island (New Zealand) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199103-241040.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
Light ashfall was reported at 2000 on 20 March by the crew of a fishing boat on the S side of the island, and continued as of 22 March. Visits to the volcano on 21 and 22 March revealed that the emission originated from a new vent (Orca) in a gully on the W side of the 1978/91 Crater. When first noted 13 February, the 20-25-m-wide vent had been the site of high heat flow and strong emission of white vapor. The March ash was not pumiceous or highly vesiculated, but it was rich in fresh glass in comparison with February tephra from TV1 Crater. Geologists suggested that the relatively fresh glass and the westward progression of activity was possibly due to new magma near the surface in the area of the new vent. Activity at TV1 Crater and the fumarole area NW of TV1 (on the floor of 1978/91 Crater) had declined to weak vapor emission on 22 March.
Seismic records were limited to 7-14 March by equipment difficulties. One small E-type event was recorded on 11 March, but no tremor was detected. Post-21 March seismograms (after equipment repair) indicated no change in the level of seismicity.
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, DSIR Geology & Geophysics, Rotorua.