Report on White Island (New Zealand) — 4 December-10 December 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 December-10 December 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on White Island (New Zealand). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 4 December-10 December 2019. Smithsonian Institution and US Geological Survey.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
A deadly and short-lived (1-2 minutes) eruption at White Island began around 1411 on 9 December, prompting GeoNet to raise the Alert Level to 4 and the Aviation Color Code to Orange. The eruption originated from the crater floor and generated an ash plume that rose 3.7 km (12,000 ft) above the vent. Ashfall was confined to the island and covered the crater floor based on webcam views. Activity waned after the event and within a few hours the Alert Level was lowered to 3. An exclusion zone extending just under 10 km around the island was emplaced for all (non-police) vessels.
The New Zealand Police stated that 47 local and international people in a tour group were on the island at the time of the eruption. A majority of the people in the group were seriously injured and taken to area hospitals; six were confirmed dead. On 10 December the police concluded that there likely were no additional survivors after several reconnaissance flights conducted post-eruption; nine people remained missing and assumed to be on the island.
On 10 December GeoNet reported that although seismic activity had dropped to low levels after the eruption, localized steaming and mud jetting continued from the active vents. Tremor significantly increased starting around 0400 on 11 December. Results from an overflight to collect gas emission data, along with other monitoring data collected over time, suggested that a shallow magma source was driving the tremor, gas emissions, and jetting activity.
Geologic Background. The uninhabited White Island, also known as Whakaari in the Maori language, 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 summit crater appears to be breached to the SE, because the shoreline corresponds to the level of several notches in the SE crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of eruptions since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. Formation of many new vents during the 19th and 20th centuries has produced 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.