White Island was inspected from the air on 25 August and from the ground on 28 August. A large but brief ash eruption from Christmas Crater began at 1445 on 25 August. Steam emission had been moderate to voluminous during the two previous weeks and a deep red glow was reported by pilots beginning about 1 week before the eruption. Pilot Bruce Black reported that the ash column, which included a few jets of incandescent material, rose rapidly to about 4,500 m before being blown NNW by a 40 km/hr wind. A few minutes later, a second explosion produced a cloud that reached 6,000 m altitude, but contained less incandescent material. Base surges from this cloud moved across the main crater, some of them against the wind. By 1515, activity had declined to steam emission.

Ground inspection revealed light gray ash, about half the thickness of the late July deposits containing lithic blocks up to 1 m in diameter. Impact craters with subdued outlines were common, the largest about 3 m in diameter and 1 m deep. Base surges had deposited moderately well-developed cross bedded transverse dunes. Slumping and a mudflow deposit were observed NW of Christmas Crater, and strong steam emission was occurring from the associated concentric cracks.

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: I. Nairn, E. Lloyd, B. Houghton, and P. van der Werff, NZGS, Rotorua.