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Volcano Hazards Program

Find U.S. Volcano

There are about 170 potentially active volcanoes in the U.S. The mission of the USGS Volcano Hazards Program is to enhance public safety and minimize social and economic disruption from volcanic unrest and eruption through our National Volcano Early Warning System. We deliver forecasts, warnings, and information about volcano hazards based on a scientific understanding of volcanic behavior.

News

Volcano Watch — Mauna Loa has lessons to teach during quiet times

Volcano Watch — Mauna Loa has lessons to teach during quiet times

Photo & Video Chronology — February 16, 2026 — Kīlauea episode 42 fountains and fallout

Photo & Video Chronology — February 16, 2026 — Kīlauea episode 42 fountains and fallout

Volcano Watch — New Hawaii citizen science tool: Is Tephra Falling?

Volcano Watch — New Hawaii citizen science tool: Is Tephra Falling?

Publications

Forecasting volcanic activity in Germany—A multi-criteria approach Forecasting volcanic activity in Germany—A multi-criteria approach

Igneous activity, including shallow intrusions and volcanism, has the potential to disrupt underground critical infrastructure. Notably, future underground infrastructure projects like high-level radioactive waste repositories must be sited in areas of extremely low disruption probability by igneous activity. In Germany, according to the Repository Site Selection Act of 2017...
Authors
A. Bartels, L.H. Rummel, F. Mayle

A comparison of non-contact methods for measuring turbidity in the Colorado River A comparison of non-contact methods for measuring turbidity in the Colorado River

Monitoring suspended-sediment concentration (SSC) is essential to better understand how sediment transport could adversely affect water availability for human communities and ecosystems. Aquatic remote sensing methods are increasingly utilized to estimate SSC and turbidity in rivers; however, an evaluation of their quantitative performance is limited. This study evaluates the performance...
Authors
Natalie K. Day, Tyler V. King, Adam R. Mosbrucker

Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau

A detailed characterization of the >3,000 square kilometer (km2) Springerville volcanic field, located on the southern tip of the Colorado Plateau in Arizona, United States, with its more than 501 volcanic units and widely distributed >420 cinder cones and lava flows, provides constraints toward an integrated petrogenetic model for the field. Large-volume effusive tholeiitic eruptions at...
Authors
Marissa E. Mnich, Christopher D. Condit
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Melt Inclusion Page

Reprints of two review articles on melt inclusions

Lowenstern, J.B., 2003, Melt inclusions come of age: Volatiles, Volcanoes, and Sorby's Legacy, In: B. De Vivo and R.J. Bodnar (eds). Melt Inclusions in Volcanic Systems: Methods, Applications and Problems. Developments in Volcanology 5, Elsevier Press, Amsterdam, pp. 1-22.

A 6 Megabyte pdf version of this website (the original review article) is available here.

The Melt Inclusion Page

About Melt Inclusions

Formation of Silicate-Melt Inclusions

  • Types of Inclusions,
  • Entrapment Mechanisms,
  • Leaked or "Hourglass Inclusions"
  • Does the Melt Inclusion Trap Representative Liquid?
  • Changes in Melt Inclusions After Entrapment

  • Volumetric Behavior
  • Other Origins of Bubbles
  • Crystallization
  • Diffusional Reequilibration
  • Techniques for Study

  • Sample Preparation
  • Electron Microprobe Analysis,
  • Ion Microprobe
  • Fourier Transform Infrared Spectroscopy
  • Other Analytical Techniques
  • Heating Stage
  • Concentrations of Dissolved Volatiles in MI

    Evidence for Fluid Saturation and Degassing

  • Mass-Balance Contraints
  • Fluid Solubility and Buffering Paths,
  • Trapped Vapors and Hypersaline Liquids
  • Petrologic and Stratigraphic Studies

  • Magma Mixing and Crystal Fractionation
  • Experimental Petrology
  • Stratigraphic Correlations
  • Melt Inclusions in Granites and Xenolithic Ejecta

    Summary

    Acknowledgements

    References

    Adapted from: Lowenstern, J.B.(1995) Applications of silicate melt inclusions to the study of magmatic volatiles. In: Thompson, J.F.H. (ed.) Magmas, Fluid and Ore Deposits. Mineralogical Association of Canada Short Course 23, 71-99.

    This article is adapted from Chapter 4 of Volume 23 of the Geological Association of Canada/ Mineralogical Association of Canada (GAC/MAC) Short Course Series. For more information, please refer to: Lowenstern (1995)

    Table 1: Data obtainable and not obtainable from silicate-melt inclusions.

    Table 2: Volatile concentrations in a variety of recently studied silicic magmas, as determined by analysis of silicate MI.

    Table 3. Summary of recent studies of volatile concentrations and saturation pressures in unleaked MI from high-silica rhyolites.

    Figure 1. Melt inclusions in quartz.

    Figure 2. Growth forms of crystals that trap MI.

    Figure 3. Hourglass inclusions.

    Figure 4. PT behavior of MI.

    Figure 5. Homogenization of an MI.

    Figure 6. Decrepitation of an MI.

    Figure 7. Crystallization of an MI.

    Figure 8. H2O vs. CO2 for a group of MI from the Pine Grove system, UT.

    Figure 9. Features within a vapor bubble.

    Other Photos of Melt Inclusions. Cool Pics!

    Volcano Hazards Program | U.S. Geological Survey Skip to main content
    U.S. flag

    An official website of the United States government

    Volcano Hazards Program

    Find U.S. Volcano

    There are about 170 potentially active volcanoes in the U.S. The mission of the USGS Volcano Hazards Program is to enhance public safety and minimize social and economic disruption from volcanic unrest and eruption through our National Volcano Early Warning System. We deliver forecasts, warnings, and information about volcano hazards based on a scientific understanding of volcanic behavior.

    News

    Volcano Watch — Mauna Loa has lessons to teach during quiet times

    Volcano Watch — Mauna Loa has lessons to teach during quiet times

    Photo & Video Chronology — February 16, 2026 — Kīlauea episode 42 fountains and fallout

    Photo & Video Chronology — February 16, 2026 — Kīlauea episode 42 fountains and fallout

    Volcano Watch — New Hawaii citizen science tool: Is Tephra Falling?

    Volcano Watch — New Hawaii citizen science tool: Is Tephra Falling?

    Publications

    Forecasting volcanic activity in Germany—A multi-criteria approach Forecasting volcanic activity in Germany—A multi-criteria approach

    Igneous activity, including shallow intrusions and volcanism, has the potential to disrupt underground critical infrastructure. Notably, future underground infrastructure projects like high-level radioactive waste repositories must be sited in areas of extremely low disruption probability by igneous activity. In Germany, according to the Repository Site Selection Act of 2017...
    Authors
    A. Bartels, L.H. Rummel, F. Mayle

    A comparison of non-contact methods for measuring turbidity in the Colorado River A comparison of non-contact methods for measuring turbidity in the Colorado River

    Monitoring suspended-sediment concentration (SSC) is essential to better understand how sediment transport could adversely affect water availability for human communities and ecosystems. Aquatic remote sensing methods are increasingly utilized to estimate SSC and turbidity in rivers; however, an evaluation of their quantitative performance is limited. This study evaluates the performance...
    Authors
    Natalie K. Day, Tyler V. King, Adam R. Mosbrucker

    Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau

    A detailed characterization of the >3,000 square kilometer (km2) Springerville volcanic field, located on the southern tip of the Colorado Plateau in Arizona, United States, with its more than 501 volcanic units and widely distributed >420 cinder cones and lava flows, provides constraints toward an integrated petrogenetic model for the field. Large-volume effusive tholeiitic eruptions at...
    Authors
    Marissa E. Mnich, Christopher D. Condit
    Was this page helpful?