Prior to October 2006, three parallel Volcano warning schemes were used by the
United States Geological Survey and the volcano observatories for different
volcano ranges in the
United States. They each have a base level for dormant-quiescent states and three grades of alert.
Color Code Conditions, Long Valley Caldera and Mono-Inyo Craters Region, California Developed in 1997 to replace a previous 5-level system devised in 1991.
Level of Concern Color Codes for volcanoes in Alaska The
Alaska Volcano Observatory (AVO) used the following color-coded system to rate volcanic activity. It was originally established during the 1989-90 eruption of
Redoubt Volcano. All five classifications are spelled as
proper nouns, i.e., Level of Concern Color Code Orange not Level of concern color code Orange or any other variation. On its website the AVO spells the alert color in all capitals, but this is not otherwise necessary outside their system.
Warning system for Cascade Range volcanoes in Washington and Oregon Introduced following the May 18, 1980,
eruption of
Mount St. Helens. ==References==