On 17 April GeoNet reported that during the previous few months gas-and-steam emissions at Whakaari/White Island more frequently contained ash. The webcams located at Whakatane and Te Kaha recorded an increase in ash content in the emissions during the last few weeks and minor amounts of ash were identified in satellite data as reported by the Wellington Volcanic Ash Advisory Center (VAAC). A hazy plume drifting downwind was visible from the mainland coast. Impact craters visible on the main crater floor during recent observation flights indicated that explosive activity had ejected rocks several hundreds of meters from the vent. Additionally, there were increases in temperatures (based on thermal infrared data) and sulfur dioxide emissions (detected by satellite and overflights). Recent activity was consistent with a low level of eruptive activity; the Volcanic Alert Level was raised to 3 (on a scale of 0-5) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale). 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