Whakaari/White Island: Vent temperature and gas output decreases, volcanic unrest continues

Whakaari/White Island after the December 2019 eruption. Photo / George Novak

The active vent temperature of Whakaari/White Island has fallen more than 300C in the past few weeks, an observation flight has found.

Data shows a substantial decrease in the vent temperature and a small decrease in gas output.

The state of moderate to heightened unrest continues and the volcanic alert level remains at level 2, a Geonet report said.

Last week, GNS Science researchers took flights around the volcano to collect visual observations, measure the levels of gas being emitted and the temperature of the active vent area.

The maximum vent temperature was 191C, a decline from 516C in December. During September-November, temperatures ranged from 202C to 264C. Temperatures over 500C were also recently observed in July and August.

Both sulphur dioxide and carbon dioxide gas emission rates were slightly below the 10-year average, a slight decrease from the output measured in December.

The temperature and gas emission observations were consistent with hot gas continuing to be released from the molten rock - magma - beneath the volcano at variable rates.

"Minor amounts of ash emission continue to be observed, similar to most of our recent observation flights," the report said.

"Ash deposits remain limited to areas close to the active vents. Further intermittent ash [emissions] may continue to occur."

The water level of the lake has also fallen during the recent spell of fine, dry weather.

The aviation colour code remains yellow.

As reported previously, the on-island equipment has degraded, meaning that while data is being collected it is not real-time and not complete. Geonet is working on restoration options.