NZGS personnel flew over White Island on 28 September. Since the previous inspection on 6 August, moderate ash emission had apparently been almost continuous. On 3-4 September, Sam Harvey of Whakatane observed a stronger ash eruption that produced a 2-km-high cloud. Seismic activity between the two inspections was characterized by prolonged bursts of high-frequency tremor [the most vigorous starting on 25 September at 1239 and lasting about 4.5 hours], interspersed with infrequent quieter periods of up to a few hours duration.

Eruptive activity during the 10-minute overflight consisted of spasmodic ejection of a pale brown, weakly convoluting gas and ash column that rose about 400 m before being blown NE by a light wind. Reddish-brown tephra appeared to uniformly mantle the main crater floor. No impact craters or other evidence of coarse ejecta were observed. Steam rose from a gully that enters 1978 Crater from the W, but pre-existing fumaroles on the main crater floor seemed unchanged.

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: E. Lloyd, NZGS, Rotorua.