White Island could still erupt with no warning
New observations since July show continued but relatively low levels of volcanic activity at Whakaari/White Island.
The Volcanic Alert Level remains at 1.
“Over the last six weeks, we have conducted three gas flights and one observation flight,” says GNS Science duty volcanologist Yannik Behr.
“Results from the gas flights indicate that magma beneath the volcano still degasses at fairly high rates.
“The vent system above the magma appears to be open, allowing the gas to escape relatively unobstructed. During fine weather conditions this will generate moderate to large gas-steam plumes above the island.”
Thermal infrared images from the active vent area, taken during the observation flight, remain high at around 440 °C, about 100 °C less than those measured in July.
Within the measurement uncertainty, this is consistent with a slowly cooling active vent area, says Yannik.
“Some of the primary gas vents continue to slowly enlarge. Rainfall events have ponded water on the crater floor forming a lakelet. Minor areas of gassing and heating can be seen in the lakelet.
“Ground deformation data from satellite measurements over the past six weeks indicate continued subsidence around the active vent area as well as ongoing subsidence of the Main Crater wall, south and west of the 2019 active vents.”
The level of volcanic seismic tremor has remained generally low, aside from a short episode of moderate volcanic tremor in early August.
Although current indications are that activity is generally decreasing, an eruption could still occur with little or no warning, says Yannik.
He says the main plausible triggers for a sudden eruption remain the collapse of unstable material from the crater walls onto the vents, increased release of gas from the shallow magma, and the ingress of water underground onto the shallow magma body.
“Overall, recent observations are consistent with minor volcanic unrest and, therefore, the Volcanic Alert Level remains at 1 and the Aviation Colour Code remains at Green.
“The Volcanic Alert Level reflects the current level of volcanic unrest or activity and is not a forecast of future activity.”
Volcanic Alert Level 1 indicates the primary hazards are those expected during volcanic unrest; steam discharge, volcanic gas, earthquakes, landslides and hydrothermal activity.
While Volcano Alert Level 1 is mostly associated with environmental hazards, eruptions can still occur with little or no warning.