Brad Scott and Sally Potter explain New Zealand's Volcanic Alert Levels.
New Zealand Volcanic Alert System
Most Likely Hazards
Major volcanic eruption
Eruption hazards on and beyond volcano*
Moderate volcanic eruption
Eruption hazards on and near volcano*
Minor volcanic eruption
Eruption hazards near vent*
Moderate to heightened volcanic unrest
Volcanic unrest hazards, potential for eruption hazards
Minor volcanic unrest
Volcanic unrest hazards
No volcanic unrest
Volcanic environment hazards
An eruption may occur at any level, and levels may not move in sequence as activity can change rapidly.
Eruption hazards depend on the volcano and eruption style, and may include explosions, ballistics (flying rocks), pyroclastic density currents (fast moving hot ash clouds), lava flows, lava domes, landslides, ash, volcanic gases, lightning, lahars (mudflows), tsunami, and/or earthquakes.
Volcanic unrest hazards occur on and near the volcano, and may include steam eruptions, volcanic gases, earthquakes, landslides, uplift, subsidence, changes to hot springs, and/or lahars (mudflows).
Volcanic environment hazards may include hydrothermal activity, earthquakes, landslides, volcanic gases, and/or lahars (mudflows).
*Ash, lava flow, and lahar (mudflow) hazards may impact areas distant from the volcano.
This system applies to all of New Zealand's volcanoes. The Volcanic Alert Level is set by GNS Science, based on the level of volcanic activity. For more information, see geonet.org.nz/volcano for alert levels and current volcanic activity, gns.cri.nz/volcano for volcanic hazards, and getthru.govt.nz for what to do before, during and after volcanic activity. Version 3.0, 2014.