Report on Whakaari/White Island (New Zealand) — November 1999
Bulletin of the Global Volcanism Network, vol. 24, no. 11 (November 1999)
Managing Editor: Richard Wunderman.
Whakaari/White Island (New Zealand) Fumarolic activity continues; new crater lake
Please cite this report as:
Global Volcanism Program, 1999. Report on Whakaari/White Island (New Zealand) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 24:11. Smithsonian Institution.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
No eruptions have occurred at White Island since the minor ash emissions in July-August 1999 from the PeeJay vent area. This report includes observations following a visit on 23 November to service the seismic installation, conduct a deformation survey, collect volcanic gas samples, and assess the general status of volcanic activity on the island.
During the visit a weak steam-and-gas plume was rising 300-500 m. This plume originated from fumarolic vents NW of the former PeeJay vents. Since the last surveillance visit in July a crater lake has developed on the floor of 1978/90 Crater Complex, inundating Metra Crater and parts of the PeeJay vent area. A series of strand lines around the crater lake edge indicated a recent drop in the lake level. Small collapse pits had recently formed near the lakeshore, below the Sag area, and may have accompanied the recent drop in lake level. The lake is a lime green color, with minor convection evident. A temperature of 45°C was measured, down slightly from the previous measurements.
The strongest fumarolic vents were on the NW side of the PeeJay vents area, emerging from the vent wall, which is ~10-15 m high. There were three prominent vents, which were emitting steam and gas that were weakly transparent at the vent. At times the steam and gas plume appeared a yellow color. The emissions were audible from 2-300 m distance. Temperatures of Main Crater fumaroles ranged from 103-115°C, and are similar to previous measurements this year.
A ground-deformation survey was also made. Eight pegs were replaced, as these were damaged during the April-July 1999 eruptions. The survey results showed that subsidence continued at the E-SE margin of the 1978/90 Crater Complex, but at a lesser rate than observed in 1998. Over the remainder of the Main Crater floor weak subsidence was also apparent at many of the marks.
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: Brad Scott, Wairakei Research Center, Institute of Geological and Nuclear Sciences (IGNS), Private Bag 2000, Wairakei, New Zealand (URL: http://www.gns.cri.nz/).