USGS Volcano Warning Scheme for the United States

The United States Geological Survey

United States Geological Survey

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 (USGS) has adopted a common system nationwide for characterizing the level of unrest and eruptive activity at volcanoes. The new volcano alert-level system is now used by the Alaska Volcano Observatory

Alaska Volcano Observatory

The Alaska Volcano Observatory is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys...

, the Cascades Volcano Observatory

Cascades Volcano Observatory

The David A. Johnston Cascades Volcano Observatory is the volcano observatory that monitors volcanoes in the Cascade Range. It is part of the United States Geological Survey, a scientific agency of the United States government. It is located in Vancouver, Washington in the Portland, Oregon...

, the Hawaiian Volcano Observatory

Hawaiian Volcano Observatory

The Hawaiian Volcano Observatory is a volcano observatory located at Uwekahuna Bluff on the rim of Kīlauea Caldera on the Island of Hawaii. The observatory monitors four active Hawaiian volcanoes: Kīlauea, Mauna Loa, Hualālai, and Haleakalā...

, the Long Valley Observatory

Long Valley Observatory

The Long Valley Observatory is the volcano observatory that monitors the volcanic and geologic activity of the Long Valley Caldera of Eastern California.The volcano observatory is east of the Sierra Nevada in Mono County, California...

, and the Yellowstone Volcano Observatory

Yellowstone Volcano Observatory

The Yellowstone Volcano Observatory monitors the Yellowstone Caldera in Yellowstone National Park in the United States. It is part of the United States Geological Survey, a scientific agency of the United States government.-References:...

.


Under the new system, the USGS ranks the level of activity at a U.S. volcano using the terms "Normal", for typical volcanic activity in a non-eruptive phase; "Advisory", for elevated unrest; "Watch", for escalating unrest or a minor eruption underway that poses limited hazards; and, "Warning", if a highly hazardous eruption is underway or imminent (Table 1). These levels reflect conditions at a volcano and the expected or ongoing hazardous volcanic phenomena. When an alert level is assigned by an observatory, accompanying text will give a fuller explanation of the observed phenomena and clarify hazard implications to affected groups.

Summary of Volcanic Activity Alert-Notification System

NORMAL	Typical background activity of a volcano in a non-eruptive state After a change from a higher level: Volcanic activity considered to have ceased, and volcano reverted to its normal, non-eruptive state.
ADVISORY	Elevated unrest above known background activity After a change from a higher level: Volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
WATCH	Heightened/escalating unrest with increased potential for eruptive activity (timeframe variable) OR a minor eruption underway that poses limited hazards.
WARNING	Highly hazardous eruption underway or imminent.

Aviation Color Codes

Code	Description
GREEN	Volcano is in its normal "dormant" state or, after a change from a higher level: Volcanic activity considered to have ceased, and volcano reverted to its normal, non-eruptive state.
YELLOW	Volcano is exhibiting signs of elevated unrest above known background levels. or, after a change from a higher level: Volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
ORANGE	Volcano is exhibiting heightened unrest with increased likelihood of eruption, or, Volcanic eruption underway with no or minor ash emission (specify ash-plume height if possible).
RED	Eruption is forecast to be imminent with significant emission of ash into the atmosphere likely. or, Eruption is underway with significant emission of ash into the atmosphere (specify ash-plume height if possible).

Earlier Volcano Warning Schemes for the United States

Prior to October 2006, three parallel Volcano warning schemes were used by the United States Geological Survey

United States Geological Survey

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 and the volcano observatories for different volcano

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 ranges in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. They each have a base level for dormant-quiescent states and three grades of alert.

Color-Code Conditions, Long Valley Caldera and Mono-Inyo Craters Region, California

Developed in 1997 to replace a previous 5-level system devised in 1991.

Code	Narrative	Levels
GREEN	No immediate risk	Levels from Quiescent to Strong Unrest
YELLOW	Watch	Intense Unrest
ORANGE	Warning	Accelerating intense unrest: eruption likely within hours to days
RED	Eruption in progress	Levels 1 (Minor eruption) - 4 (Massive explosive eruption)

Level of Concern Color Codes for volcanoes in Alaska

The Alaska Volcano Observatory

Alaska Volcano Observatory

The Alaska Volcano Observatory is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys...

 (AVO) used the following color coded system to rate volcanic activity. It was originally established during the 1989-90 eruption of Redoubt Volcano

Mount Redoubt (Alaska)

Mount Redoubt, or Redoubt Volcano, is an active stratovolcano in the largely volcanic Aleutian Range of the U.S. state of Alaska. Located in the Chigmit Mountains , the mountain is just west of Cook Inlet, in the Kenai Peninsula Borough about 180 km southwest of Anchorage...

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Class	Description
GREEN	Volcano is in its normal "dormant" state.
YELLOW	Volcano is restless. Seismic activity is elevated. Potential for eruptive activity is increased.
ORANGE	Small ash eruption expected or confirmed. Plume(s) not likely to rise above 25,000 feet above sea level.
RED	Large ash eruptions expected or confirmed. Plume likely to rise above 25,000 feet above sea level.

All five classifications are spelled as proper noun

Proper noun

A proper noun or proper name is a noun representing a unique entity , as distinguished from a common noun, which represents a class of entities —for example, city, planet, person or corporation)...

s, i.e., Level of Concern Color Code Orange not Level of concern color code Orange or any other variation. On its website the AVO spells the alert color in all capitals, but this is not otherwise necessary outside their system.

Warning system for Cascade Range volcanoes in Washington and Oregon

Introduced following the May 18, 1980, eruption of Mount St. Helens

Mount St. Helens

Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is south of Seattle, Washington and northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a...

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Code	Narrative	Levels
No Alert	"Information Statements" may be issued about unusual but non-threatening events
Alert Level ONE	Notice of Volcanic Unrest	Significant anomalous conditions are recognized that could be indicative of an eventual hazardous volcanic event.
Alert Level TWO	Volcano Advisory	Monitoring and evaluation indicate that processes are underway that have significant likelihood of culminating in hazardous volcanic activity but when the evidence does not indicate that a life- or property-threatening event is imminent.
Alert Level THREE	Volcano Alert	Monitoring and evaluation indicate that precursory events have escalated to the point where a volcanic event with attendant volcanologic or hydrologic hazards threatening to life and property appears imminent or is underway.