Volcano Alert Levels of the United States Geological Service (USGS)

The United States Geological Survey (USGS) issues a volcano alert notice (VAN) to describe the risk associated with a volcano.

Alert levels:

(1) normal

(2) advisory

(3) watch

(4) warning

Volcano Status	Term
typical background, noneruptive	Normal
any signs of elevated unrest above background level	Advisory
increasing potential for eruption	Watch
nonhazardous eruption	Watch
hazardous eruption imminent, underway or suspected	warning
decrease in volcanic activity so no longer hazardous	Watch
decrease in volcanic activity with potential to have renewed activity	Watch
significant decrease in volcanic activity with continued monitoring to detect renewed increase	advisory
cessation of volcanic activity with return to typical background	normal

To read more or access our algorithms and calculators, please log in or register.