AVO News

AVO will now rank the level of activity at Alaskan volcanoes using the terms NORMAL, ADVISORY, WATCH, and WARNING.

These terms, defined below, are assigned based on observations, instrumental monitoring data, and the known history and potential hazards of each volcano.

Alert levels address the overall activity at the volcano, not just the hazard to aviation. There may be situations where a volcano is producing lava flows that are dangerous on the ground and merit a WATCH or WARNING, however, the hazard to aviation is minimal.

Alert levels announcements will always contain additional explanation of volcanic activity and expected hazards.

NORMAL Typical background activity of a volcano in a non-eruptive state.
Or, after a change from a higher level:
Volcanic activity considered to have ceased, and volcano reverted to its normal, non-eruptive state.

ADVISORY Elevated unrest above known background activity.
Or, after a change from a higher level:
Volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.

WATCH Volcano is exhibiting heightened or escalating unrest with increased potential for eruptive activity.
Or:
A minor eruption is underway that poses limited hazards.

WARNING Highly hazardous eruption underway or imminent.

LEVEL OF CONCERN COLOR CODES FOR AVIATION

AVO will continue to use the color-coded level of concern designation that has been in place since 1990.

Colors will now reflect only the hazards posed to the aviation community.

Typically, this means that color codes indicate the likelihood or presence of airborne ash and ash clouds that threaten aircraft. Definitions of each color are below.

GREEN Volcano is in a normal, non-eruptive state.
Or, after a change from a higher level:
Volcanic activity considered to have ceased and volcano reverted to its normal, non-eruptive state.

YELLOW Volcano is exhibiting signs of elevated unrest above known background levels.
Or, after a change from a higher level:
Volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.

ORANGE Volcano is exhibiting heightened unrest with increased likelihood of eruption.
Or:
Volcanic eruption underway with no or minor ash emission.

RED Eruption is forecast to be imminent with significant emission of ash into the atmosphere likely
Or:
Eruption is underway with significant emission of ash into the atmosphere.

For more information and background on this new system, please see:
http://volcanoes.usgs.gov/2006/vhpalertlevel.pdf