The U.S. Geological Survey (USGS) Volcano Hazards Program has adopted an alert-notification system nationwide for characterizing the level of unrest and eruptive activity at volcanoes. The four-tiered Volcano Alert Level uses the terms Normal, Advisory, Watch, and Warning.
The Volcano Alert Levels are intended to inform people on the ground about a volcano’s status and are issued in conjunction with the Aviation Color Code. Notifications are issued for both increasing and decreasing volcanic activity and are accompanied by text with details about the nature of the unrest or eruption and about potential or current hazards and likely outcomes.
The 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.
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.
The ADVISORY / YELLOW icon is used when a volcano is exhibiting signs of elevated unrest above known background activity.
The WATCH / ORANGE icon is used when a Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, time frame uncertain OR an eruption is underway that poses limited hazards including no or minor volcanic-ash emissions.
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).
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.
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.
The Aviation Color Code notifications are issued in conjunction with the Volcano Alert Levels. The color codes (Green, Yellow, Orange, Red – see Table) are used to provide succinct information about volcanic-ash hazards to the aviation sector. Volcanic activity threatens safe air travel when finely pulverized, glassy, abrasive volcanic material is explosively erupted into the atmosphere and dispersed as airborne clouds in flight paths of jet aircraft. The color codes are in accord with recommended ICAO (International Civil Aviation Organization) procedures to help pilots, dispatchers, and air-traffic controllers who are planning or executing flights over broad regions of the globe quickly ascertain the status of numerous volcanoes and determine if continued attention, re-routing, or extra fuel is warranted.
|Table. Summary of Aviation Color Codes|
Volcano is in typical background, non-eruptive state
Volcano is exhibiting signs of elevated unrest above known background level
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, time frame uncertain,
Eruption is imminent with significant emission of volcanic ash into the atmosphere likely
The U.S. Geological Survey Volcano Hazards Program Volcano Notification Service (VNS) is a free customizable service that sends you notification emails about volcanic activity happening at US monitored volcanoes. You can receive volcano notifications for any volcanoes monitored by United States volcano observatories. Notifications are generally available within five minutes after they are released.
To receive messages about volcanic activity from the VNS, you must select the volcanoes that you are interested in. Once registered and logged in, clicking My Volcanoes in the left menu will bring you to a Google-map based page, showing volcanoes covered by the VNS.
National Volcano Early Warning System (NVEWS)
The National Volcano Early Warning System (NVEWS) is a proposed national-scale plan to ensure that volcanoes are monitored at levels commensurate to their threats. The plan was developed by the U.S. Geological Survey (USGS) Volcano Hazards Program (VHP) and its affiliated partners in the Consortium of U.S. Volcano Observatories (CUSVO).
The NVEWS plan ensures that the most hazardous volcanoes would be properly monitored well in advance of the onset of activity, making it possible for scientists to improve the timeliness and accuracy of hazard forecasts and for citizens to take proper and timely action to reduce risk.
- USGS Volcano Hazards Program – U.S. Volcanoes and Current Activity Alerts Map- http://volcanoes.usgs.gov/
- Image Source: http://volcanoes.usgs.gov/activity/alertsystem/index.php [Accessed August 23, 2013]
- USGS Volcanic Activity Alert-Notification System: http://volcanoes.usgs.gov/activity/alertsystem/
- Volcano Notification Service (VNS) – http://volcanoes.usgs.gov/vns/
- National Volcano Early Warning System (NVEWS) – http://volcanoes.usgs.gov/publications/2009/nvews.php
- Image Source: http://volcanoes.usgs.gov/vns/help.php [Accessed August 23, 2013]