Increased ash emission and local seismicity were continuing in late January. Long periods of semi-continuous, moderate- to high-frequency tremor continued from the 12th, but were punctuated on 16 January by 19 possible explosion-type earthquakes between 0052 and 1738 (the largest at 0451). On 22 January there were 6 explosion events (maximum amplitude less than half that of the largest 16 January event) from 1158 to 1222, and tremor gradually declined to low levels after 0800 on the 23rd. Eleven hours later, however, tremor amplitude increased for 2 1/4 hours, then remained continuous at moderate to high frequency for over 5 days. A single explosion-type event occurred at 1015 on 26 January and tremor declined to a low level at 0500 on the 29th. [The largest B-type shock of the period, M 2.45, occurred during a 3-hour swarm of about 50 similar events on 24 February.]

On 23 and 25 January an ash column rose to about 600 m above sea level from the active vent, which was at least 50 m deep. About 40 cm of ash was measured at the rim of 1978 Crater on the 25th, 8 cm more than on 12 January. Blocks up to 1 m across, not observed on the 12th, were found about 200 m to the E. Fumarole temperatures of up to 535°C were recorded, similar to those measured on 7 December.

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. Scott and I. Nairn, NZGS, Rotorua.