Report on Whakaari/White Island (New Zealand) — 17 November-23 November 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
17 November-23 November 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, 17 November-23 November 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 results from an 18 November overflight of Whakaari/White Island, noting a decrease in gas emissions and the lake level. Gas measurements showed that sulfur dioxide emissions had decreased from 681 tons per day recorded on 2 November to 484 tons per day. Additionally, both carbon dioxide and hydrogen sulfide decreased from 2712 to 1416 tons per day and from 38 to 19 tons per day, respectively. The gas data suggested that molten material at depth continued to degas. Temperatures in the main vent area were 243-264 degrees Celsius, similar to the range (202-264 degrees Celsius) measured both in September and earlier in November. Very minor ash emissions were visible and deposits only extended around the active vents. A new vent was observed, located S of the main vent and near the base of the 2019 landslide area. Deposits around the new vent suggested that it formed by an energetic, steam-driven ejection of mud. 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.