GeoNet reported that as of 23 December, although moderate to heightened volcanic unrest continued, since the last overflight on 14 December no emissions had contained detectable ash. Satellite imagery and webcam feeds from Whakatane and Te Kaha indicated weak steam and gas emissions on December 23. During periods of clear weather, a more substantial steam plume was observed above Whakaari from the Bay of Plenty coastline. The Aviation Color Code was lowered from Orange (the third level on a four-level scale) to Yellow (the second level on a four-level scale). The Volcanic Alert Level remained at Level 2 (the third level on a six-level scale).

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