During 5 hours of observation by geologists and geophysicists on 21 October, the active vent in 1978 Crater emitted an ash-poor gas column of varying intensity which deposited no tephra. Gray ash postdating the 11 September inspection was 1 cm thick on the 1978 Crater rim, and less than 2 mm thick beyond 200 m from the rim. No fresh impact craters were observed. Fumarolic activity continued from the gas vents NE of 1978 Crater that were first observed in May and other gas vents remained vigorous. Fumarole temperatures were generally somewhat lower than in May and September with a maximum of 600°C.

A levelling survey showed that the relatively rapid rate of subsidence (as much as 2.3 mm/week) between May and September, which had followed 6 weeks of localized inflation, decreased to less than 1 mm/week in the 6 weeks since 11 September. Magnetic field intensity appeared to have fallen near the 1978 Crater rim since 11 September.

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.

Information Contacts: B. Houghton, I. Nairn, NZGS, Rotorua.