Report on Whakaari/White Island (New Zealand) — 2 December-8 December 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
2 December-8 December 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Whakaari/White Island (New Zealand). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 2 December-8 December 2020. 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 Whakaari/White Island observations and monitoring data indicated a gradual trend to lower activity levels during the previous two weeks. An overflight of the island on 2 December confirmed that ash emissions stopped and were not visible in satellite images during 2-7 December. Volcanic tremor levels and the number of local earthquakes decreased. Deformation data indicated subsidence around the active vents and parts of the Main Crater wall. Hot steam-and-gas emissions persisted. The Volcanic Alert Level was lowered to 1 and the Aviation Color Code was lowered to Green on 7 December.
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.