White Island volcano (Whakaari) remains in an elevated state of unrest, but no further extrusion of lava has occurred. GNS' assessment is that further explosive eruptions remain very unlikely on any given day. The Volcanic Alert Level remains at Level 2 and the Aviation Colour Code remains at Yellow. However, this reflects the current level of volcanic activity and is not a forecast of future activity.
"We undertook visual observation and gas flights last week and confirm no further extrusions of lava has occurred," GNS Duty Volcanologist Natalia Deligne noted on February 4, 2020. "Gas fluxes are lower than two weeks ago but remain elevated. Apart from minor ash emissions on December 23 and 26, 2019, no explosive eruptive activity has been detected or observed since the December 9, 2019 eruption."
Although measurements made on January 30 show gas outputs have decreased they still remain at high levels, as expected after an eruption and the extrusion of fresh magma. The temperatures associated with the lava extrusions remain very hot (greater than 550 - 570 °C / 932 - 1 058 °F). Aerial observations confirm no changes to the crater vent area, the receding lake, or lava extrusion.
Image credit: GNS
Satellite data shows continued land movement of the west wall of the Main Crater and the 1914 landslide scarp. "We continue to monitor the rate of movement, which has not changed in displacement rate, nor were changes noted on the latest observation flight. GNS Science landslide experts are assessing the likelihood of future landslides into the active vent area."
Although very unlikely, an explosive eruption from the active vent area remains possible and could occur with no precursory activity, Deligne stated.
"This style of the eruption could be driven by the collapse of unstable material around the vents, or by a marked decrease in gas emissions allowing water from the geothermal system to enter the active hot gas vents. There is very little water in the former lake basin at present.
The number of casualties after the eruption on December 9th rose to 21 on January 28, after another person died as a result of injuries.
There were 47 people visiting the island when the volcano erupted, killing 13 people initially and leaving more than two dozen others hospitalized with severe burns. Many of the killed and injured were Australian tourists who had been traveling aboard the Royal Caribbean cruise ship Ovation of the Seas.
Uninhabited 2 x 2.4 km (1.2 x 1.5 miles) White Island, one of New Zealand's most active volcanoes, is the emergent summit of a 16 x 18 km (10 x 11.2 miles) submarine volcano in the Bay of Plenty about 50 km (31 miles) 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 (3.1 miles) 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. (GVP)
Featured image credit: GNS