Report on Whakaari/White Island (New Zealand) — 14 July-20 July 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
14 July-20 July 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, 14 July-20 July 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 continuing unrest at Whakaari/White Island. During overflights of the island on 15 and 20 July scientists observed minor steam-and-gas activity around the 2019 Primary Crater lava domes and noted that the Main Crater area continues to fill with water. Other fumarolic vents remained active and unchanged. Overall, seismicity was at low levels during the previous few months, punctuated by a few notable events; a short-lived tremor episode was recorded on 2 June, discrete acoustic signals recorded during 18-20 June were associated with geysering in a new vent N of 2019 Crater, and a 15-minute low-frequency volcanic earthquake occurred on 30 June. Nighttime incandescence has persisted in webcam views since the 30 June earthquake. Thermal infrared measurements taken on 15 July confirmed that temperatures at dome vents had notably increased, from around 110 degrees Celsius measured in late May-early June to 498-654 degrees. Gas emissions had not notably changed over the previous few months as confirmed during the 20 July overflight. The Volcanic Alert Level remained at 1 and the Aviation Color Code remained at Green.
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.