Report on Whakaari/White Island (New Zealand) — July 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 7 (July 1994)
Managing Editor: Richard Wunderman.
Whakaari/White Island (New Zealand) No eruptive activity, but new shifts in leveling and magnetic data
Please cite this report as:
Global Volcanism Program, 1994. Report on Whakaari/White Island (New Zealand) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 19:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199407-241040.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
Routine monitoring visits on 23 April and 28 June 1994 found no evidence of any eruptive activity. On 23 April the floor of Princess Crater was occupied by a muddy pond that contained fresh landslide debris (see figure 21). The divide between Wade and Royce craters had been destroyed. Active fumaroles included those in TV1 Crater, and those escaping from beneath landslide debris in the Royce area.
Scientists who made brief trips on 12 and 15 May noted 5-10 m subsidence of the lake occupying the active vent area on the floor of Wade Crater; the lowered lake level persisted until at least 29 May. A triangulation survey on 28 June determined the lake to be 56 m below sea level and 92 m below the rim of the 1978/90 Crater Complex.
Deformation was surveyed in nearly ideal conditions on 28 June, achieving a good error of closure; the results showed that since 19 January 1994 a subtle but significant crater-wide uplift, typically 5-10 mm, has taken place. Stronger uplifts occurred at Donald Mound (+15 mm) and SE of Peg M (+21 mm). This kind of crater-wide inflation was last seen in the three years preceding the 1976-93 eruptions.
A magnetic survey of established sites revealed a pattern of net magnetic changes very similar to the two previous periods of measurements in 1993. A negative anomaly lay to the N of Donald Mound (-100 nT), and a positive one to the S (+60 nT). P. Rickerby noted that "these anomalies could be interpreted as resulting from shallow heating under Donald Mound (~50 m deep) and shallow cooling under TV1."
Seismicity recorded during January-June 1994 has generally showed little change; tremor in this interval has remained near background, though it has been present on 54% of the obtained records.
Geologic Background. 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: T. Hunt, B. Scott, T. Kabayashi, and T. Tosha, IGNS, Wairakei; P. Rickerby, Victoria Univ, Wellington.