In New Zealand, Volcano Alert Bulletins (VABs) are the official source of warnings and alerts including current Volcanic Alert Level (VAL),^[1] intended to inform stakeholder agencies, authorities, and the public about emergencies so they can take action.

The examples and perspective in this article deal primarily with New Zealand and do not represent a worldwide view of the subject. (January 2024)

The Ministry of Civil Defence & Emergency Management, through The National Emergency Management Agency is responsible for providing such alerts to warn about natural hazards.^[2] A Scientific Alert Level is applied to the Volcano Status based on Indicative Phenomena. GNS Science operates the national geological hazards monitoring network (GeoNet).^[3]

The Volcanic Alert Level system has six levels ranging from 5 (major volcanic eruption) to 0 (no volcanic activity):^[4]

To help prevent harm when living or working on or near a volcano, countries have adopted classifications to describe the various levels and stages of volcanic activity, the two main volcano warning systems being colour codes and/or numeric alert levels. ^[7]

• United States Alert System
• Indonesia Alert System ^[8]
• Russia
• Alaska Alert System
• Vanuatu Volcanic Alert Level
• Colombia Alert System ^[7]

The three common popular classifications of volcanoes can be subjective, and some volcanoes thought to have been extinct have erupted again.