On 20 July GeoNet reported that continuing unrest at Whakaari/White Island was characterized by low-level gas-and-steam emissions and decreasing temperatures during the previous month. The temperatures at the large vents declined from 240 degrees Celsius in March to 120 degrees in late June. During an overflight on 18 July steam-and-gas plumes were observed rising from the same vents in the active crater area as previously observed and the discharge rates were relatively unchanged. No evidence of ash emissions or eruptive activity were observed.

After the remaining monitoring instruments on the island failed, observations were made during overflights, from the webcam located on Whakatane, and using satellite data. Significant changes in deformation or sulfur dioxide emissions were not detected in satellite data over the past few months. The Volcanic Alert Level remained at 2 (on a scale of 0-5) and the Aviation Color Code remained at Yellow (the second level on a four-color scale). GeoNet noted that the Alert Levels reflected the level of unrest at the volcano but also considered the greater level of uncertainty in activity due to the current lack of consistent and useful real-time data.

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