On 24 February GeoNet reported that large, white, steam-rich plumes from Whakaari/White Island were visible in the Whakatane and Te Kaha webcams during the past week. On several of those days sulfur dioxide emissions were detected in satellite data and sulfur odors were noted by residents along the coast. During 22-23 February those plumes also contained small amounts of ash as reported by the Wellington VAAC and visible as a faint haze from the coast. The activity was consistent with moderate to heightened levels of unrest, therefore the Volcanic Alert Level remained at 2 (on a scale of 0-5). At 1430 on 24 February the Aviation Color Code was raised to Orange (the second highest level on a four-color scale) due to the presence of ash in the emissions. GeoNet stated that the Alert Levels were reflective of the current level of activity, but there was uncertainty due to the current lack of consistent, usable, real-time monitoring data; GeoNet relies on remote cameras, satellite images, and occasional overflights to monitor Whakaari.

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