Report on Whakaari/White Island (New Zealand) — August 1977
Natural Science Event Bulletin, vol. 2, no. 8 (August 1977)
Managing Editor: David Squires.
Whakaari/White Island (New Zealand) Entire island covered in ash in late July
Please cite this report as:
Global Volcanism Program, 1977. Report on Whakaari/White Island (New Zealand) (Squires, D., ed.). Natural Science Event Bulletin, 2:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.NSEB197708-241040.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
There were inspections from the air on 5 and 26 July, and from the ground on 3 August. At 1117 on 5 July, Mr. Harvey, Civil Defence Whakatane, observed an ash column that rose rapidly to an estimated 1200 m. The crater and the base of the column appeared to be glowing. Mr. D. Thursby viewed White Island at 1150 from Te Kaha, about 50 km away, and reported a dense, red ash cloud that dispersed after rising about 300 m. The aircraft reached White Island at 1534. A pink, moderately convoluting cloud, interspersed with higher velocity ash pulses, was rising 300-400 m. A thick layer of deeply channeled red ash covered the main crater floor. No large ejecta or bomb craters were observed, nor was there any incandescence.
During the 26 July aerial inspection, ash content of the plume was reduced to an orange tint near the base. Brick-red ash, thought to be several days old, covered the island. No new impact craters were noted.
The 3 August ground inspection revealed that the gullied red ash seen from the air on 5 and 26 July had been covered by coarse gray tephra, field identified as glassy basaltic andesite, ranging from ash to blocks (up to l m in diameter) and bombs. Some of the gray tephra initially deposited on the main crater walls had been remobilized to form debris flows, about 3 m wide at their fronts and usually less than 100 m long, that had moved down pre-existing debris fans towards the crater floor. Pits dug at several locations in the main crater revealed that more than 82 cm of ash had fallen near Christmas Crater since 5 May. The gray tephra layer comprised 37 of the 82 cm, and was overlain by 2-5 mm of fine red ash.
The ash column on 3 August was light tan, and was emitted at moderate velocity to about 600 m. No incandescence was observed.
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: J. Cole, Victoria Univ., Wellington; B. Scott and B. Houghton, NZGS, Rotorua.