Volcano Hazards

Alert Level Icons

Volcano Alert Levels

Volcano updates include both a Volcano Alert Level and an Aviation Color Code. In most cases, the alert level and aviation-specific color code will move together (e.g., Normal and Green; Advisory and Yellow; Watch and Orange; Warning and Red). However, there may be occasions when the hazards to ground-based communities and the aviation sector differ.

The following combination of alert level icons are used on our interactive website maps to depict a volcano's status. 

NORMAL / GREEN Non-erupting volcano is exhibiting typical background activity (including steaming, seismic events, thermal feature, or degassing), as long as such activity is within the range of typical non-eruptive phenomena seen at the volcano.
ADVISORY / YELLOW Volcano is exhibiting signs of elevated unrest above known background activity.
WATCH / ORANGE Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain OR an eruption is underway that poses limited hazards including no or minor volcanic-ash emissions.
WARNING / ORANGE Major volcanic eruption is imminent, underway, or suspected but it poses limited hazards to aviation because of no or minor volcanic-ash emissions (e.g., an eruption with only substantial lava flows and no risk of ash production).
WATCH / RED Volcanic eruption is underway that poses limited hazards to ground-based communities but includes significant emission of ash into the atmosphere that could affect aviation (e.g. an ash plume that does not yield significant ash fall onto ground communities but does drift into air routes.
WARNING / RED Major volcanic eruption is imminent, underway, or suspected with hazardous activity both on the ground and in the air.
UNASSIGNED Volcanoes where ground-based instrumentation is insufficient to establish that a volcano is in a typical background level (GREEN / NORMAL). When activity at such a volcano increases to the point of being detected by remote sensing, distant seismic networks, or eyewitness reports, an alert level and color code are then assigned accordingly. When activity decreases, the volcano goes back to UNASSIGNED without going through GREEN / NORMAL.