GeoNet’s latest volcanic alert bulletin has changed the Aviation Colour Code to Green for Whakaari/White Island. This is a result of a “continuously decreasing level of volcanic activity”. This change in Aviation Colour Code comes a week after the Volcanic Alert Level was dropped to level 1
The Volcanic Alert Level 1 indicates that the most likely hazards are those expected during lower levels of volcanic unrest, for example, steam discharge, volcanic gases, earthquakes, landslides and hydrothermal activity. GeoNet stress that while Volcano Alert Level 1 is associated with these environmental hazards, it doesn’t rule out the possibility of eruptions occurring with little or no warning.
Despite the decision to lower the Aviation Colour Code, an eruption could still occur with little or no advanced warning. Plausible triggers for an 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 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.
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