GeoNet reported that on 6 September scientists visited White Island for routine monitoring and maintenance of the monitoring network. Observations during the visit confirmed that Crater Lake was growing though at a lower level (28.4 m below the overflow level) since the 27 April eruption removed 13-15 m of lake floor sediments. Thermal IR images of a rocky lava mound in the back of the 1978/90 Crater (in the same area a lava dome grew in 2012) revealed two areas of hot gas output; temperatures in one area had decreased since August while temperatures in the second area had remained at similar levels.

On 13 September minor and passive ash emissions rose from the vent on the 2012 lava dome. The Volcanic Alert Level was raised from 1 to 3 (Minor Volcanic Eruption) and the Aviation Colour Code was raised from Green to Orange. Based on ground observations and satellite data the ash plume drifted E. Seismic activity and gas flux remained low, and there were no measureable acoustic signals. Minor ash emissions continued the next day.

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