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Report on Whakaari/White Island (New Zealand) — October 1988

Whakaari/White Island

Scientific Event Alert Network Bulletin, vol. 13, no. 10 (October 1988)
Managing Editor: Lindsay McClelland.

Whakaari/White Island (New Zealand) Ash emission; earthquake swarms

Please cite this report as:

Global Volcanism Program, 1988. Report on Whakaari/White Island (New Zealand) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 13:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198810-241040

Whakaari/White Island

New Zealand

37.52°S, 177.18°E; summit elev. 294 m

All times are local (unless otherwise noted)

Since geologists last visited ... on 14 August, no eruptions have been reported although numerous E-type (explosion) earthquakes have occurred. During fieldwork on 14 October, a continuous expanded gas plume containing fine pink ash rose from Hitchhiker vent. Brick-red ash covered the island's E half and small impact craters were scattered ESE of the vent. Tephra ejected after 1 August was 70 mm thick at Congress Crater's rim and included altered lithic fragments, abraded crystals, and a few % fresh, light brown, highly vesicular scoria fragments. High pressure/temperature gas was emitted from fumaroles roughly 200 m E of Hitchhiker vent, including two new vents. Gas vents were surrounded by aprons of material ranging from anhydrite-cemented ash to lithic blocks.

Since early August, an average of seven B-type and fewer than five high-frequency A-type seismic events have been recorded/day. Earthquake swarms were detected 24-25 August (62 events), 7-8 September (38 events), and 23-24 September (57 events followed by E-type earthquakes). Of 20 E-type events recorded in August, 16 occurred 12-24 August. Four E-type events were recorded in September and one on 2 October, before ash accumulation on solar panels suspended operation of seismic instruments on 4 October.

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 and B. Scott, NZGS Rotorua.