Report on White Island (New Zealand) — 6 February-12 February 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 February-12 February 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on White Island (New Zealand). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 6 February-12 February 2013. Smithsonian Institution and US Geological Survey.
37.52°S, 177.18°E; summit elev. 321 m
All times are local (unless otherwise noted)
On 11 February GeoNet Data Centre reported that analysis of recent changes and measurements from White Island indicated that activity was lower than the previous week; therefore, the Aviation Colour Code was lowered to Yellow and the Volcanic Alert Level remained at 1 (on a scale of 0-5). The report also stated that early during the previous week the level of volcanic tremor recorded at White Island dropped to less than half that of the week before. At the same time small explosive eruptions in the active crater, which had been occurring for about three weeks, became less intense. On 7 February sulfur dioxide and carbon dioxide gas measurements were similar to measurements from January: sulfur dioxide flux was 560 tonnes/day and carbon dioxide flux was 1,800 tonnes/day. A volcanologist that visited the lake area on 8 February noted that water had again filled the lake and small geysering was the only activity that he observed. The lake water was hot, about 80 degrees Celsius.
Geologic Background. Uninhabited 2 x 2.4 km White Island, one of New Zealand's most active volcanoes, is the 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 summit crater appears to be breached to the SE, because the shoreline corresponds to the level of several notches in the SE crater wall. Volckner Rocks, four sea stacks that are remnants of a lava dome, lie 5 km NNE. Intermittent moderate phreatomagmatic and strombolian eruptions have occurred throughout the short historical period beginning in 1826, but its activity also forms a prominent part of Maori legends. Formation of many new vents during the 19th and 20th centuries has produced 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.