Report on Whakaari/White Island (New Zealand) — December 1993
Bulletin of the Global Volcanism Network, vol. 18, no. 12 (December 1993)
Managing Editor: Edward Venzke.
Whakaari/White Island (New Zealand) Temperature rises in crater lake; no new eruptive activity
Please cite this report as:
Global Volcanism Program, 1993. Report on Whakaari/White Island (New Zealand) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 18:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199312-241040
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
No eruptive activity has been reported through mid-December, although further collapse of the N and NE margin of the 1978/90 Crater Complex was noted on 1 December. There have been no ash emissions since a phreatic eruption on 19 October. Following that event, the lake in Wade Crater was generally yellow with a temperature around 22°C (table 10). By 27 November, the temperature was over 50°C, and there was geyser-like activity near the W shore. Lake color had changed to bright green or green-yellow by 1-2 December, with the temperature remaining high and strong bubbling and effervescence near the W shore. Examination of photographs indicated that the lake level may have risen 2-5 m between October and December.
|30 Jul 1993||Bright green||--||Lake 90 m below rim|
|27 Aug 1993||--||45.5°C||--|
|19 Oct 1993||--||--||PHREATIC ERUPTION|
|22 Oct 1993||Bright orange-yellow||23°C||Lake 110-130 m below rim|
|27 Oct 1993||Yellow-brown||21.5°C||--|
|03 Nov 1993||--||22.5°C||--|
|27 Nov 1993||Mustard-yellow||52.1°C||Geyser-like activity near W shore|
|01 Dec 1993||Bright green||--||--|
|02 Dec 1993||Bright green-yellow||53.1°C||Level rise of 2-5 m, bubbling near W shore|
Royce Crater was occupied by water on 1 and 2 December, a new development since 27 November, and the former fumarole vent was discharging through the pond. A tour operator reported possible impact craters in the Donald Mound-Donald Duck area on 12 December as well as a significant increase in steam emission and noise from vents in Royce Crater between visits on 10 and 12 December, indicating that the pond may have dried up around the active fumaroles. Fumarole temperatures declined slightly between 22 October and 2 December. During a visit on 3 November, the single circular fumarole on the E wall of Wade Crater above the twin fumaroles was an estimated 5-10 m in diameter and clearly visible.
Three precision proton magnetometers were installed on 3 November to provide continuous recording of magnetic field strength changes at frequent intervals. The instruments are located 22 m from the NE edge of the 1978/90 Crater Complex, just inside the SW sector of Noisy Nellie crater, and in the NE side of Main Crater ~100 m from the coast. A magnetic survey on 2 December measured 85 locations, including 10 new marker pegs. Most of the notable magnetic trends seen from the previous survey (30 August 1993) have continued at comparable rates. The most notable trends were a -90 nT anomaly N of Donald Mound and a +40 nT anomaly S of Donald Mound that indicated heating centered at a depth of ~50 m. A positive anomaly NE of TV1 Crater indicated continued shallow cooling in the active vent area.
Conditions during the deformation survey on 2 December were excellent, allowing good closures of all three circuits. Strong subsidence centered in the Donald Mound area continued to dominate the deformation pattern, although the rate had decreased since the exceptionally high rate recorded a year earlier in the Donald Duck-TV1 area. The subsidence was attributed to a combination of local cooling, withdrawal of underlying brine fluids, and subterranean collapse. An area centered ~200 m SE of Donald Mound has continued to inflate at a steady rate of 1.7 mm/month since first noted in January 1993. This inflation was tentatively attributed to increased heating at a depth of ~200 m.
Trial COSPEC measurements were attempted on 2 December from the crater floor and from a helicopter. Although SO2 signals were recorded during ground-based measurements, calibration was impossible due to strong winds causing turbulent dispersal of SO2 throughout the crater. Vertical measurements from the helicopter were also unacceptable due to interference from the main rotor. Measurements from a fixed-wing aircraft on 8 December were more successful; the plume was being displaced by a 5-knot wind. Seven passes were made beneath the plume at altitudes of 200-250 m above the ocean surface at ground speeds of 75-103 knots. The average SO2 flux from three scans considered to be reliable was 171 ± 26 t/d.
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. Scott and C. Wood, IGNS Wairakei.