On 23 March GeoNet reported that volcanologists observed Whakaari/White Island and took gas measurements during overflights the week before. The active vent area had subsided, and small collapses in one of the 2019 craters had occurred in between the flights. During the second flight, scientists observed geysering from a small, gray-colored pool on the S side of the main crater. In just over an hour the pool was gone and a collapse pit was in its place. Diffuse ash emissions had ceased. Gas and temperature measurements were lower (290 degrees Celsius) compared to the previous month. The Volcanic Alert Level remained at 2 and the Aviation Color 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