The GeoNet Data Centre reported that a small eruption from White Island occurred at 1023 on 20 August and continued for about 10 minutes. The eruption ejected mud and rocks short distances, and generated a voluminous steam plume (visible from the Bay of Plenty coast), that rose 4 km a.s.l. and then slowly dispersed. Weather radar observations showed that a minor amount of ash was present in the plume. The Volcano Alert Level was raised to 2 (on a scale of 0-5) and the Aviation Colour Code was raised to Red (on a four-color scale). Later that day the Aviation Colour Code was lowered to Orange.

The eruption originated in the active crater area that had been ejecting small amounts of mud in recent weeks. A short period of strong volcanic tremor was detected the previous morning, but it was not clear if it was related to the eruption.

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