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Latest Earthquake | Chat Share
The U.S. Geological Survey (USGS) employs a nationwide volcano alert-level system for characterizing conditions (quiet, unrest, eruption) at U.S. volcanoes. Notifications about the status of activity at U.S. volcanoes are issued through the five regional U.S. Volcano Observatories. Additional information on the alert-notification system can be found in the Fact Sheet U.S. Geological Survey's Alert-Notification System for Volcanic Activity.
The USGS alert-level system for volcanic activity has two parts – 1) ranked terms to inform people on the ground about a volcano's status and 2) ranked colors to inform the aviation sector about airborne ash hazards.