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Volcano Hazards Program

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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.

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Ash-rich plume rises out of Halemaʻumaʻu Crater, Kilauea Volcano Hawaiʻi

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Mount Rainier seen from Puyallup, Washington

Long-term hazards assessments identify locations at risk from volcanic hazards. They are released as high-resolution hazards-zonation maps with accompanying explanations, which help guide eruption preparedness plans.

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Volcano Observatory staff monitor, research, and issue formal notices of activity for volcanoes in assigned geographic areas. Scientists also assess volcano hazards and work with communities to prepare for volcanic eruptions.

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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?

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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
By
Volcano Hazards Program, Volcano Science Center

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
By
Volcano Hazards Program, Volcano Science Center, Colorado Water Science Center, Idaho Water Science Center, Cascades Volcano Observatory

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
By
Volcano Hazards Program, Volcano Science Center
View All
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Melt Inclusions Summary

  • MELT INCLUSIONS IN GRANITES AND XENOLITHIC EJECTA
  • SUMMARY
  • ACKNOWLEDGEMENTS

    • Melt Inclusions in Granites and Xenolithic Ejecta

    For the most part, MI are absent in granitic rocks because their prolonged cooling history allows complete crystallization of the inclusions, erasing any record of their existence (Tuttle 1952). Only in rapidly cooled intrusions will MI remain intact and unaltered. In the ~280-Ma Mount Genis granite in southeastern Sardinia, Frezzotti (1992) found MI (some glassy) within equigranular granites as well as in crystals lining miarolitic cavities. Coexisting brine was interpreted as having formed during the late stages of crystallization of the magma. The MI were analyzed by EPMA, and several of them contained typical high-silica rhyolite glass with Cl concentrations reflecting equilibrium with vapor and hydrosaline melt (Shinohara 1994). Hansteen & Lustenhouwer (1990) examined MI and coexisting aqueous inclusions from the Permian Eikeren-Skrim granite in Norway. The inclusions homogenized at 685-705 °C, were composed of rhyolitic and rhyodacitic glass (not peralkaline) and were trapped at the same time as a saline aqueous fluid. Eadington & Nashar (1978) described and analyzed glass inclusions from topaz-quartz rocks from the New England district of New South Wales in Australia. Many of the MI contained several wt.% F, as well as apparent high H2O concentrations. Weisbrod (1981) reviewed several studies of coexisting fluid and melt inclusions in shallow intrusions and porphyry deposits. Takenouchi & Imai (1975) described MI from a variety of porphyry and volcanic rocks and observed the effects of cooling history on the characteristics of MI.

    Occasionally, intrusive rocks are ejected as xenoliths during volcanic eruptions. Studies of such samples have often resulted in discovery of CO2-rich fluids in equilibrium with melt in the environment where the xenoliths grew (Roedder 1965; Belkin et al. 1985; Frezzotti et al. 1991; Belkin and De Vivo 1993). Other xenoliths show evidence for immiscibility between silicate melt and hypersaline fluids (Roedder & Coombs 1967) or entrapment of both phases, though at different times (De Vivo et al. 1993).

     

    Summary

    Silicate MI contain information on the dissolved volatile concentrations in igneous rocks (Tables 2 and 3). A variety of analytical and thermometric methods can be used to extract information from MI, as regards magmatic volatile concentrations, the compositions of exsolved magmatic fluids and the pressure and temperature conditions under which magmas undergo crystallization. New techniques promise to increase the number of possible uses of MI, lengthening the first half of Table 1 and shortening its last half. For example, given improving microbeam techniques, MI may contribute new data on the stable-isotopic (H, O, S, Cl) composition of non-degassed magmas, and the effect of degassing on the isotopic composition of silicate melt. New microbeam dating methods may allow assessment of the time delay between crystallization (MI formation) and eruption. Combined with the ever-increasing data-set on volatile solubilities, MI may yield more reliable estimates of the depths to magma chambers than are currently available through mineral geobarometers. As such, MI are likely to remain one of the most useful and reliable methods for understanding the behavior of volatile components in igneous systems and will continue to provide insight for economic geologists, volcanologists and other geoscientists.

    Acknowledgements

    Discussions over the past 7 years have helped me to clarify my thinking about MI; I thank A.T. Anderson, C.R. Bacon, D.K. Bird, P. Fiske, G.A. Mahood, S. Newman, E. Roedder, H. Shinohara, T. Sisson, J. Stebbins, and P.J. Wallace for their input. The rest of my education about MI has been the legacy of excellent papers by A.T. Anderson, E. Roedder, R. Clocchiatti and others, as well as the interesting samples I've had the good fortune to study. I appreciate reviews of the manuscript and helpful comments by C. Bacon, K. Bargar, H. Belkin, B. Bodnar, J. Hedenquist, H. Shinohara, and S. Simmons.

    Volcano Hazards Program | U.S. Geological Survey Skip to main content
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    The map displays volcanoes, earthquakes, monitoring instruments, and past lava flows.

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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.

    Learn more about NVEWS

    Volcano Activity Notifications

    Ash-rich plume rises out of Halemaʻumaʻu Crater, Kilauea Volcano Hawaiʻi

    USGS Volcano Observatories release regular updates and notifications to communicate increases or decreases in volcanic activity and explain unusual or hazardous circumstances. 

    Get Latest Updates

    Volcano Hazards Assessments

    Mount Rainier seen from Puyallup, Washington

    Long-term hazards assessments identify locations at risk from volcanic hazards. They are released as high-resolution hazards-zonation maps with accompanying explanations, which help guide eruption preparedness plans.

    View Assessments

    U.S. Volcano Observatories

    Volcano Observatory staff monitor, research, and issue formal notices of activity for volcanoes in assigned geographic areas. Scientists also assess volcano hazards and work with communities to prepare for volcanic eruptions.

    Learn More

    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?

    View All

    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
    By
    Volcano Hazards Program, Volcano Science Center

    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
    By
    Volcano Hazards Program, Volcano Science Center, Colorado Water Science Center, Idaho Water Science Center, Cascades Volcano Observatory

    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
    By
    Volcano Hazards Program, Volcano Science Center
    View All
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