On 21 October the GeoNet Data Centre reported that no further eruptive activity at White Island was detected after the eruption on 11 October, which ejected material over 350 m from the active vent and caused a wet surge cloud that enveloped the Main Crater. Volcanic tremor levels had decreased after the eruption and continued at variable levels. Gas flight measurements on 17 October showed that the SO2 flux was 450 tonnes per day, CO2 was 1,140 tonnes per day, and H2S was12 tonnes per day. The SO2 and H2S flux had changed very little, and CO2 had decreased from the previous measurements on 23 August. The Volcanic Alert Level was lowered to 1 and the Aviation Colour 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.

Source: GeoNet