USGS Volcano Notification Service informs island residents about Hawaiian volcan
Detailed Description
The USGS Alert-Notification System for Volcanic Activity includes Volcano Alert Levels, which rank a volcano's status for people on the ground, and Aviation Color Codes, which rank airborne ash hazards for the aviation sector. This four-tiered system ranges from Normal/Green to Warning/Red to indicate increasing level of concern. To learn more, please visit https://volcanoes.usgs.gov/vhp/about_alerts.html.
Sources/Usage
Public Domain.