The Art (and Science) of Assigning Volcano Alerts Levels
The four-tiered USGS Volcanic Activity Alert-Notification System uses Volcano Alert Level terms and Aviation Color Codes to inform people about a volcano's status and potential volcanic ash hazards. For more information about this system, please see http://pubs.usgs.gov/fs/2006/3139/. The status of Mauna Loa on the Island of Hawai‘i was recently elevated to ADVISORY/YELLOW. USGS graphic.