On 16 August GeoNet reported that a modest increase in ash content of emissions at Whakaari/White Island began on 9 August, based on satellite data. The gas-and-ash plumes rose as high as 2 km above the vent and drifted tens of kilometers from the island. Higher concentrations of volcanic gas emissions were detected during a 14 August gas observation overflight compared to the last overflight on 18 July. The emissions rose from a new vent that was 10-15 m in diameter and contained minor amounts of ash. Analysis of an ash sample collected during the overflight indicated a shallow magma source; the recent data confirmed that eruptive activity had changed around the beginning of August. The Volcanic Alert Level remained at 3 (on a scale of 0-5) and the Aviation Color Code remained at Orange (the second highest level on a four-color 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