At least 50 discrete high-frequency earthquakes were recorded between 0034 and 0608 on 5 October. Large events occurred at 0037, 0250, and 0424. With the possible exception of the second event, the shocks had very sharp onsets and were interpreted as A-type events. The earthquake swarm was followed by bursts of low-amplitude volcanic tremor, which continued sporadically through the rest of the day.

An aerial inspection on 5 October revealed no new tephra or impact craters. A white, gently convoluting steam cloud rose from fumaroles in 1978 crater and at the base of the main crater wall, north of Noisy Nellie. Yellow and white fumarole sublimates covered the walls of 1978 Crater.

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.