Report on Whakaari/White Island (New Zealand) — 18 August-24 August 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
18 August-24 August 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Whakaari/White Island (New Zealand). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 August-24 August 2021. Smithsonian Institution and US Geological Survey.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
GeoNet maintained the Volcanic Alert Level at 2 and the Aviation Color Code at Yellow for Whakaari/White Island. A volcanic earthquake was recorded at 1900 on 19 August that continued for ten minutes; other seismic activity has been minor. Webcam images showed some incandescence during the night, which suggested that temperatures in the vent area were likely 500-600°C. On 22 August at 0740 a period of minor ash emissions was observed from the active vent area that lasted for two minutes, based on webcam images. Low levels of ground deformation around the active vent and lake area were identified in satellite radar data.
Geological Summary. 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.