At least two moderate explosive eruptions seemed to have occurred since 12 April. R. R. Dibble and E. Hardy observed recently ejected tephra deposits on 21-22 April. [J.H. Latter notes that the strongest period of volcanic tremor recorded between August 1977 and September 1979 started at 1800 on 29 April and continued until 1 May at 0856.] A newspaper article (Whakatane Beacon, 9 May) reported that an eruption at 2030 on 1 May produced a shock wave recorded by a vessel anchored off White Island and a thin layer of ash fell on the same vessel. At 1737 the next day, S. Harvey (Civil Defence, Whakatane, ~50 km from White Island) observed an eruption column that rose to 4-5 km altitude.

NZGS personnel overflew White Island on 18 May. A low, white gas column from the active vent in 1978 Crater obscured the W portion of the main crater floor. Strong steaming also occurred from fumaroles N and E of 1978 Crater. Reddish brown tephra covered much of the visible area of the main crater, and there were post-12 April impact craters up to 2 m in diameter 1/2 km E of the active vent.

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 and I. Nairn, NZGS, Rotorua; R. Dibble and E. Hardy, Victoria Univ., Wellington; S. Harvey, Civil Defence, Whakatane; The Whakatane Beacon.