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U.S. Geological Survey Open-File Report 2009-1118

Chronology and References of Volcanic Eruptions and Selected Unrest in the United States, 1980-2008

By Angela K. Diefenbach, Marianne Guffanti, and John W. Ewert


Index map and link to PDF (935 kB)


The United States ranks as one of the top countries in the world in the number of young, active volcanoes within its borders. The United States, including the Commonwealth of the Northern Mariana Islands, is home to approximately 170 geologically active (age <10,000 years) volcanoes. As our review of the record shows, 30 of these volcanoes have erupted since 1980, many repeatedly. In addition to producing eruptions, many U.S. volcanoes exhibit periods of anomalous activity, unrest, that do not culminate in eruptions.

Monitoring volcanic activity in the United States is the responsibility of the U.S. Geological Survey (USGS) Volcano Hazards Program (VHP) and is accomplished with academic, Federal, and State partners. The VHP supports five Volcano Observatories—the Alaska Volcano Observatory (AVO), Cascades Volcano Observatory (CVO), Yellowstone Volcano Observatory (YVO), Long Valley Observatory (LVO), and Hawaiian Volcano Observatory (HVO). With the exception of HVO, which was established in 1912, the U.S. Volcano Observatories have been established in the past 27 years in response to specific volcanic eruptions or sustained levels of unrest. As understanding of volcanic activity and hazards has grown over the years, so have the extent and types of monitoring networks and techniques available to detect early signs of anomalous volcanic behavior. This increased capability is providing us with a more accurate gauge of volcanic activity in the United States.

The purpose of this report is to (1) document the range of volcanic activity that U.S. Volcano Observatories have dealt with, beginning with the 1980 eruption of Mount St. Helens, (2) describe some overall characteristics of the activity, and (3) serve as a quick reference to pertinent published literature on the eruptions and unrest documented in this report.

Version 1.0

First posted July 1, 2009

This report is available only on the Web.

For additional information contact:
Angie Diefenbach

Volcano Hazards Program

This report is presented in Portable Document Format (PDF); at least version 7 of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Diefenbach, A.K., Guffanti, Marianne, and Ewert, J.W., 2009, Chronology and references of volcanic eruptions and selected unrest in the United States, 1980-2008: U.S. Geological Survey Open-File Report 2009-1118, 85 p. [].


Part I



     Eruptions and Unrest


     References Cited

Part II

     References of Volcanic Eruptions and Unrest, 1980-2008

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