Icons for USGS Volcanic Activity Alert-Notification System
Volcano updates include both a Volcano Alert Level and an Aviation Color Code. In most cases, the alert level and aviation-specific color code will move together (e.g., Normal and Green; Advisory and Yellow; Watch and Orange; Warning and Red). However, there may be occasions when the hazards to ground-based communities and the aviation sector differ.
When activity at a volcano poses a hazard to the aviation community that is significantly higher than the hazard to ground-based communities, a Volcano Watch and Aviation Color Code Red may be issued. An example would be an ash plume that does not yield significant ash fall onto ground communities but does drift into air routes. Conversely, a large lava flow heading towards a town that is unlikely to produce any ash in flight routes or near an airport might necessitate a Volcano Warning in effect with an Aviation Color Code of Orange.
The tables and descriptions below show the six different combinations of terms and colors that are possible to describe levels of activity at a volcano. The icons were created using a letter or image for the volcano alert level and an increasing triangle size in conjunction with the color for the aviation color code. For more information about the Volcano Alert Levels and Aviation Color Codes, please see the USGS Volcanic Activity Alert-Notification System.
NORMAL / GREEN
The NORMAL / GREEN icon is used when a non-erupting volcano is exhibiting typical background activity (including steaming, seismic events, thermal feature, or degassing), as long as such activity is within the range of typical non-eruptive phenomena seen at the volcano.
ADVISORY / YELLOW
The ADVISORY / YELLOW icon is used when a volcano is exhibiting signs of elevated unrest above known backround activity.
WATCH / ORANGE
The WATCH / ORANGE icon is used when a Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain OR an eruption is underway that poses limited hazards including no or minor volcanic-ash emissions.
WARNING / ORANGE
The WARNING / ORANGE icon is used when a major eruption is imminent, underway, or suspected but it poses limited hazards to aviation because of no or minor volcanic-ash emissions (e.g., an eruption with only substantial lava flows).
WATCH / RED
The WATCH / RED icon is used when an eruption is underway that poses limited hazards to ground-based communities but includes significant emission of ash into the atmosphere that could affect aviation
WARNING / RED
The WARNING / RED icon is used when a major eruption is imminent, underway, or suspected with hazardous activity both on the ground and in the air
The UNASSIGNED icon is used for volcanoes where ground-based instrumentation is insufficient to establish that a volcano is in a typical background level (GREEN / NORMAL). When activity at such a volcano increases to the point of being detected by remote sensing, distant seismic networks, or eye witness reports, an alert level and color code are then assigned accordingly. When activity decreases, the volcano goes back to UNASSIGNED without going through GREEN / NORMAL.