Report on Whakaari/White Island (New Zealand) — 9 December-15 December 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 December-15 December 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Whakaari/White Island (New Zealand). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 9 December-15 December 2015. Smithsonian Institution and US Geological Survey.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
On 10 December the GeoNet Data Centre reported that minor unrest continued at White Island based on results from recent routine monitoring. During the previous week scientists visited the island and detected continuing (over the previous three months) ground deformation and a small increase in CO2 soil gas flux. Small temperature increases were also measured at the hottest fumarole and from the lake water. Volcanic tremor levels fluctuated, but overall showed a consistent rise over the last two months; they remained below those observed in 2012 when unrest was stronger and small eruptions occurred. Airborne gas measurements revealed an increase in CO2 and a decrease in SO2 gas fluxes. The Volcanic Alert Level remained at 1 and the Aviation Colour Code remained Green.
Geologic Background. 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.