Whakaari/White Island's Aviation Colour Code changes to green

As volcanic unrest on Whakaari/White Island continues to gradually decrease, the island's Aviation Colour Code has changed to green. But another eruption has not been completely ruled out.

GNS Science announced the change in colour code today. It follows the drop in Volcanic Alert Level to 1 last Tuesday, the first time since November last year.

A Whakaari White Island crater floor webcam image at 12.20pm yesterday. Photo / GeoNet

The Aviation Colour Code is used by the aviation industry while the alert system describes the level of volcano activity and potential hazards.

Monitoring data over the last few months shows Whakaari/White Island continues to gradually decrease to lower levels of volcanic unrest.

The decision to lower the colour code is not as a result of recent changes in a single data set but is based on the GNS Science volcano monitoring team's interpretation of data and trends over the past few months.

Aerial view of Whakaari/White Island after the volcanic eruption on December 9. Photo / File

It indicates the most likely hazards are those expected during lower levels of volcanic unrest such as steam, volcanic gases, earthquakes and landslides.

But it does not completely rule out the possibility of eruptions happening with little or no warning, according to the GNS Science volcanic alert bulletin.

It does not show the level of risk but that the volcano is no longer exhibiting moderate-heightened signs of unrest.

Possible triggers for an eruption are still the collapse of unstable material from the crater walls onto the vents, an increased release of gas from the shallow magma, and the movement of water onto the shallow magma body.

"Should any explosive activity produce an ash cloud, the likelihood of ash affecting the
mainland remains very low.

"Under suitable weather conditions, the gas and steam plume may be noticed on the mainland as weak acid rain."