White Island was inspected from the air on 26 July and visited on 6 and 9 August. Impact craters not present on 28 June were visible in 26 July airphotos. The time of the eruption that produced the craters is uncertain. However, a 4,500-m black eruption column was seen from the mainland by one observer, about 50 km away, at 1045 on 17 July.

Numerous impact craters from 0.5 to 2.0 m in diameter were found during the August visits, extending E from the active vent in Gibrus crater and reaching a concentration of about 1 crater/4 m² area. Geologists excavated a few of the craters, each of which contained an angular andesite block. Poorly sorted ash- to lapilli-sized gray tephra, 10-20 mm thick near the vent, mantled the surface. The tephra deposit contained no evidence of fresh magma. According to NZGS geologists, the tephra was probably deposited by a pyroclastic flow or base surge. The impact craters contained tephra deposits only on their distal rims, indicating that the tephra's movement included a substantial horizontal component.

The narrow ridge separating Christmas and Gibrus craters was virtually destroyed between 28 June and 26 July. The NW portion of the old Christmas Crater had deepened, and was occupied by vigorous fumaroles and a series of yellowish-green ponds. Continuous fumarolic activity was observed at other sites within this new composite crater, and weaker fumaroles were active NW of it.

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, E. Lloyd, B. Scott, NZGS, Rotorua.