The Alaska Volcano Observatory issues volcano alerts via a color-coded system. Green indicates normal activity, with color changes indicating level of concern to aviators. In this image, taken April 30, 2020, all monitored volcanoes are are either green or yellow. Credit: Alaska Volcano Observatory

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The Alaska Volcano Observatory issues volcano alerts via a color-coded system. Green indicates normal activity, with color changes indicating level of concern to aviators. In this image, taken April 30, 2020, all monitored volcanoes are are either green or yellow. Credit: Alaska Volcano Observatory

The Alaska Volcano Observatory issues volcano alerts via a color-coded system. Green indicates normal activity, with color changes indicating level of concern to aviators. In this image, taken April 30, 2020, all monitored volcanoes are are either green or yellow. Credit: Alaska Volcano Observatory

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