The following U.S. volcanoes are known to be above normal background (elevated unrest or eruptions) or have shown activity that warranted an Information Release (for example, an earthquake swarm). Times are local to the volcano and in military format. Volcano Alert Levels & Aviation Color Codes defined at https://volcanoes.usgs.gov/vhp/notifications.html.

Volcano Observatory Notices for Aviation (VONA)

Volcano Observatory Notices for Aviation (VONA) are succinct, plain-English messages aimed at dispatchers, pilots, and air-traffic controllers to inform them of volcanic unrest and eruptive activity that could produce ash-cloud hazards. VONA are issued by U.S. Volcano Observatories when a volcano's Aviation Color Code is changed (up or down) or when significant change in volcanic activity occurs within a color-code level.