Report on Whakaari/White Island (New Zealand) — December 2008
Bulletin of the Global Volcanism Network, vol. 33, no. 12 (December 2008)
Managing Editor: Richard Wunderman.
Whakaari/White Island (New Zealand) Gas and mud emissions, lake level shifts from May 2007 to January 2009
Please cite this report as:
Global Volcanism Program, 2008. Report on Whakaari/White Island (New Zealand) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 33:12. Smithsonian Institution.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
The water level in the White Island crater lake had decreased significantly, especially during April 2007, and the water temperature had fallen from 74° to 64°C (BGVN 32:06). However, this activity was not accompanied by any eruptions, and monitoring had not detected any increase in volcanic activity. This report discusses activity from May 2007 through January 2009.
By late October 2007, the lake had almost completely evaporated. Then, in December 2007, the lake began to rise. By mid-February 2008, the level had risen about 6 m. Accompanying the rise in lake level was a further drop in lake temperature, from 63° to 53°C, due to the greater volume of water. The lake color changed from a turbid gray to a light green, reflecting less suspended sediment.
On 21 November 2007, an earthquake swarm (the largest, M 4.2) occurred 10 km NW of White Island. On 13 June 2008 a tectonic earthquake (M 5.4) 10 km SW was widely felt in the Bay of Plenty. However, neither earthquake event was associated with increased volcanic seismicity. From 2 December 2008 through 31 January 2009 there were a few small earthquakes 5-10 km NW of the volcano. However, dozens of epicenters occurred just offshore N of the New Zealand mainland (near Whakatane and Matata), many to the SW of White Island.
By 23 October 2008 the lake had risen 15 m (within about 9 m of overflow), and was beginning to affect the geothermal features on the Main Crater floor. New springs formed on the floor and old springs flowed again. The lake temperature was 57°C, and the water color had changed to light green, reflecting a decrease in suspended sediment.
High-temperature fumaroles (101-103°C) were located on the S floor of the Main Crater. Steam, gas, and mud emissions had increased from the largest vent during the previous few weeks. The Alert Level remained at Level 1 (low on a scale of 0-5), indicating signs of unrest. Steaming continued into February 2009 (figure 51).
|Figure 51. Photo of White Island crater taken 6 February 2009. Dinosaur toy in left foreground for scale. Courtesy of Geonet.|
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: GeoNet, a collaboration between the Earthquake Commission and GNS Science (URL: http://www.geonet.org.nz/); GNS Science, Wairakei Research Center, Private Bag 2000, Taupo 3352, New Zealand (URL: http://www.gns.cri.nz/); Earthquake Commission (EQC), PO Box 790, Wellington, New Zealand (URL: http://www.eqc.govt.nz/).