Science from Terra: A volcanic activity alert-level system for aviation: review of its development and application in Alaska

An ash cloud from an eruption of the Tungurahua volcano in Ecuador and the peak of the dormant Chimborazo volcano project through cloud cover in this photo taken from NASA's C-20A flying at 41,000 feet (12,500 meters) altitude about 100 miles (160 kilometers) northeast of Guayaquil, Ecuador on March 17, 2013. (c) NASA

In the the issue of the journal Natural Hazards published in December 2013 an article concerning the volcanic activity alert-level system for aviation. The authors are Marianne Guffanti and Thomas P. Miller from US Geological Survey. Here below the abstract.

An alert-level system for communicating volcano hazard information to the aviation industry was devised by the Alaska Volcano Observatory (AVO) during the 1989–1990 eruption of Redoubt Volcano. The system uses a simple, color-coded ranking that focuses on volcanic ash emissions: Green—normal background; Yellow—signs of unrest; Orange—precursory unrest or minor ash eruption; Red—major ash eruption imminent or underway. The color code has been successfully applied on a regional scale in Alaska for a sustained period. During 2002–2011, elevated color codes were assigned by AVO to 13 volcanoes, eight of which erupted; for that decade, one or more Alaskan volcanoes were at Yellow on 67 % of days and at Orange or Red on 12 % of days. As evidence of its utility, the color code system is integrated into procedures of agencies responsible for air-traffic management and aviation meteorology in Alaska. Furthermore, it is endorsed as a key part of globally coordinated protocols established by the International Civil Aviation Organization to provide warnings of ash hazards to aviation worldwide. The color code and accompanying structured message (called a Volcano Observatory Notice for Aviation) comprise an effective early-warning message system according to the United Nations International Strategy for Disaster Reduction. The aviation color code system currently is used in the United States, Russia, New Zealand, Iceland, and partially in the Philippines, Papua New Guinea, and Indonesia. Although there are some barriers to implementation, with continued education and outreach to Volcano Observatories worldwide, greater use of the aviation color code system is achievable.