On 25 March GeoNet reported that semi-continuous steam-and-gas plumes from Whakaari/White Island contained variable but minor amounts of ash during the previous few weeks. The plumes were visible in images from webcams (at Whakatane and Te Kaha) and occasionally detected in satellite data by the New Zealand Met Service. The ash sometimes created a hazy plume drifting downwind that could be seen from points along the mainland coast. During an overflight on 21 March scientists observed that the active event areas had slightly enlarged. They saw impact craters on the crater floor, up to 600 m from the vent, suggesting that occasional more explosive activity had recently occurred. Temperature measurements of the active vent were 360 degrees Celsius, up from 220 degrees measured in January. But well below the highs of over 580 degrees measured in August 2024. Sulfur dioxide emissions were not identified in satellite data. 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). The Aviation Color Code remained at 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 periodic 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