Report on Whakaari/White Island (New Zealand) — 1 September-7 September 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
1 September-7 September 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, 1 September-7 September 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 reported that beginning at 0630 on 2 September minor ash emissions from the active vent at Whakaari/White Island were visible in webcam images. The emissions were observed in satellite images drifting SW and reaching the Bay of Plenty coastline. GeoNet noted that short episodes of minor ash emissions had been recorded during the previous few weeks, though none were as sustained as the 2 September episode. Minor ash emissions were also recorded on 3 September, but then ceased. The webcam continued to record nighttime incandescence from the vent, at least through 6 September, suggesting that temperatures were likely 500-600°C. Steam-and-gas plumes were voluminous, and coupled with weather conditions, were easily visible from the coast. Deformation measurement showed a broad area of subsidence around the vent area, possibly from the release of pressurized gas at depth and the more voluminous plumes. Additionally, the ash emissions may have possibly been caused by wall fragments falling into the vent. The Volcanic Alert Level remained at 2 and the Aviation Color Code remained at Yellow.
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.