Geologic hazards

Mount Rainier is a large stratovolcano of andesitic rock in the Cascade Range of western Washington. Although the volcano as it now stands was almost completely formed before the last major glaciation, geologic formations record a variety of events that have occurred at the volcano in postglacial time. Repetition of some of these events today without warning would result in property damage and loss of life on a catastrophic scale. It is appropriate, therefore, to examine the extent, frequency, and apparent origin of these phenomena and to attempt to predict the effects on man of similar events in the future. The present report was prompted by a contrast that we noted during a study of surficial geologic deposits in Mount Rainier National Park, between the present tranquil landscape adjacent to the volcano and the violent events that shaped parts of that same landscape in the recent past. Natural catastrophes that have geologic causes - such as eruptions, landslides, earthquakes, and floods - all too often are disastrous primarily because man has not understood and made allowance for the geologic environment he occupies. Assessment of the potential hazards of a volcanic environment is especially difficult, for prediction of the time and kind of volcanic activity is still an imperfect art, even at active volcanoes whose behavior has been closely observed for many years. Qualified predictions, however, can be used to plan ways in which hazards to life and property can be minimized. The prediction of eruptions is handicapped because volcanism results from conditions far beneath the surface of the earth, where the causative factors cannot be seen and, for the most part, cannot be measured. Consequently, long-range predictions at Mount Rainier can be based only on the past behavior of the volcano, as revealed by study of the deposits that resulted from previous eruptions. Predictions of this sort, of course, cannot be specific as to time and locale of future events, and clearly are valid only if the past behavior is, as we believe, a reliable guide. The purpose of this report is to infer the events recorded by certain postglacial deposits at Mount Rainier and to suggest what bearing similar events in the future might have on land use within and near the park. In addition, table 2 (page 22) gives possible warning signs of an impending eruption. We want to increase man's understanding of a possibly hazardous geologic environment around Mount Rainier volcano, yet we do not wish to imply for certain that the hazards described are either immediate or inevitable. However, we do believe that hazards exist, that some caution is warranted, and that some major hazards can be avoided by judicious planning. Most of the events with which we are concerned are sporadic phenomena that have resulted directly or indirectly from volcanic eruptions. Although no eruptions (other than steam emission) of the volcano in historic time are unequivocally known (Hopson and others, 1962), pyroclastic (air-laid) deposits of pumice and rock debris attest to repeated, widely spaced eruptions during the 10,000 years or so of postglacial time. In addition, the constituents of some debris flows indicate an origin during eruptions of molten rock; other debris flows, because of their large size and constituents, are believed to have been caused by steam explosions. Some debris flows, however, are not related to volcanism at all.

@misc{doi103133b1238,
    author = "Crandell, Dwight Raymond and Mullineaux, Donal Ray",
    title = "Volcanic hazards at Mount Rainier, Washington",
    year = "1967",
    abstract = "Mount Rainier is a large stratovolcano of andesitic rock in the Cascade Range of western Washington. Although the volcano as it now stands was almost completely formed before the last major glaciation, geologic formations record a variety of events that have occurred at the volcano in postglacial time. Repetition of some of these events today without warning would result in property damage and loss of life on a catastrophic scale. It is appropriate, therefore, to examine the extent, frequency, and apparent origin of these phenomena and to attempt to predict the effects on man of similar events in the future. The present report was prompted by a contrast that we noted during a study of surficial geologic deposits in Mount Rainier National Park, between the present tranquil landscape adjacent to the volcano and the violent events that shaped parts of that same landscape in the recent past. Natural catastrophes that have geologic causes - such as eruptions, landslides, earthquakes, and floods - all too often are disastrous primarily because man has not understood and made allowance for the geologic environment he occupies. Assessment of the potential hazards of a volcanic environment is especially difficult, for prediction of the time and kind of volcanic activity is still an imperfect art, even at active volcanoes whose behavior has been closely observed for many years. Qualified predictions, however, can be used to plan ways in which hazards to life and property can be minimized. The prediction of eruptions is handicapped because volcanism results from conditions far beneath the surface of the earth, where the causative factors cannot be seen and, for the most part, cannot be measured. Consequently, long-range predictions at Mount Rainier can be based only on the past behavior of the volcano, as revealed by study of the deposits that resulted from previous eruptions. Predictions of this sort, of course, cannot be specific as to time and locale of future events, and clearly are valid only if the past behavior is, as we believe, a reliable guide. The purpose of this report is to infer the events recorded by certain postglacial deposits at Mount Rainier and to suggest what bearing similar events in the future might have on land use within and near the park. In addition, table 2 (page 22) gives possible warning signs of an impending eruption. We want to increase man's understanding of a possibly hazardous geologic environment around Mount Rainier volcano, yet we do not wish to imply for certain that the hazards described are either immediate or inevitable. However, we do believe that hazards exist, that some caution is warranted, and that some major hazards can be avoided by judicious planning. Most of the events with which we are concerned are sporadic phenomena that have resulted directly or indirectly from volcanic eruptions. Although no eruptions (other than steam emission) of the volcano in historic time are unequivocally known (Hopson and others, 1962), pyroclastic (air-laid) deposits of pumice and rock debris attest to repeated, widely spaced eruptions during the 10,000 years or so of postglacial time. In addition, the constituents of some debris flows indicate an origin during eruptions of molten rock; other debris flows, because of their large size and constituents, are believed to have been caused by steam explosions. Some debris flows, however, are not related to volcanism at all.",
    url = "https://doi.org/10.3133/b1238",
    doi = "10.3133/b1238",
    openalex = "W1588595270"
}

@misc{crossref1973map,
    title = "Map showing potential hazards from future eruptions of Mount Rainier, Washington",
    year = "1973",
    url = "https://doi.org/10.3133/i836",
    doi = "10.3133/i836",
    openalex = "W1518599953"
}

Mount St. Helens volcano in southern Washington has erupted many times during the last 4000 years, usually after brief dormant periods. This behavior pattern. suggests that the volcano, last active in 1857, will erupt again-perhaps within the next few decades. Potential volcanic hazards of several kinds should be considered in planning for land use near the volcano.

@article{doi101126science1874175438,
    author = "Crandell, Dwight Raymond and Mullineaux, Donal Ray and Rubin, Meyer",
    title = "Mount St. Helens Volcano: Recent and Future Behavior",
    year = "1975",
    journal = "Science",
    abstract = "Mount St. Helens volcano in southern Washington has erupted many times during the last 4000 years, usually after brief dormant periods. This behavior pattern. suggests that the volcano, last active in 1857, will erupt again-perhaps within the next few decades. Potential volcanic hazards of several kinds should be considered in planning for land use near the volcano.",
    url = "https://doi.org/10.1126/science.187.4175.438",
    doi = "10.1126/science.187.4175.438",
    openalex = "W2027708057"
}

@misc{crandell1976potential,
    author = "Crandell, Dwight Raymond and Mullineaux, Donal Ray",
    title = "Potential hazards from future eruptions of Mount St. Helens volcano, Washington",
    year = "1976",
    booktitle = "Open-File Report",
    url = "https://doi.org/10.3133/ofr76491",
    doi = "10.3133/ofr76491",
    openalex = "W2507922949"
}

@misc{crossref1978potential,
    title = "Potential hazards from future eruptions of Mount St. Helens Volcano, Washington",
    year = "1978",
    url = "https://doi.org/10.3133/b1383c",
    doi = "10.3133/b1383c",
    openalex = "W1483414540",
    references = "doi103133b1028n"
}

@misc{hyde1978postglacial,
    author = "Hyde, Jack H. and Crandell, Dwight Raymond",
    title = "Postglacial volcanic deposits at Mount Baker, Washington, and potential hazards from future eruptions",
    year = "1978",
    booktitle = "Professional Paper",
    url = "https://doi.org/10.3133/pp1022c",
    doi = "10.3133/pp1022c",
    openalex = "W1564040014",
    references = "doi101126science14436241334, doi10113000167606196576321lpsaci20co2, doi101130gsab501493, doi101139e68140, doi103133b1028n, openalexw624605202"
}

@misc{miller1978potential,
    author = "Miller, C. Dan",
    title = "Potential hazards from future eruptions in the vicinity of Mount Shasta Volcano, northern California",
    year = "1978",
    booktitle = "Open-File Report",
    url = "https://doi.org/10.3133/ofr78827",
    doi = "10.3133/ofr78827",
    openalex = "W2509761293"
}

@misc{crossref1980potential,
    title = "Potential hazards from future eruptions in the vicinity of Mount Shasta Volcano, Northern California",
    year = "1980",
    url = "https://doi.org/10.3133/b1503",
    doi = "10.3133/b1503",
    openalex = "W1582457429"
}

@misc{crossref1980recent,
    title = "Recent eruptive history of Mount Hood, Oregon, and potential hazards from future eruptions",
    year = "1980",
    url = "https://doi.org/10.3133/b1492",
    doi = "10.3133/b1492",
    openalex = "W2273520013",
    references = "doi10113000167606196576321lpsaci20co2, doi10113000167606196980969gapotm20co2, doi101139e77128, doi103133b1028n, doi103133b1119, doi103133b1401, openalexw587238355"
}

@techreport{miller1980potential1,
    author = "Miller, D. C",
    title = "Potential hazards from future eruptions of Mount Shasta volcano, northern California",
    year = "1980",
    howpublished = "United States Geological Survey Bulletin, v. 1503; 43 pp",
    note = "talkorigins\_source = {true}; raw\_reference = {Miller, D. C., 1980, Potential hazards from future eruptions of Mount Shasta volcano, northern California: United States Geological Survey Bulletin, v. 1503; 43 pp.}"
}

Thirteen eruptions of Mount St. Helens between June 1980 and December 1982 were predicted tens of minutes to, more generally, a few hours in advance. The last seven of these eruptions, starting with that of mid-April 1981, were predicted between 3 days and 3 weeks in advance. Precursory seismicity, deformation of the crater floor and the lava dome, and, to a lesser extent, gas emissions provided telltale evidence of forthcoming eruptions. The newly developed capability for prediction reduced risk to life and property and influenced land-use decisions.

@article{doi101126science22146181369,
    author = "Swanson, Donald A. and Casadevall, Thomas J. and Dzurisin, Daniel and Malone, S. D. and Newhall, Christopher G. and Weaver, C. S.",
    title = "Predicting Eruptions at Mount St. Helens, June 1980 Through December 1982",
    year = "1983",
    journal = "Science",
    abstract = "Thirteen eruptions of Mount St. Helens between June 1980 and December 1982 were predicted tens of minutes to, more generally, a few hours in advance. The last seven of these eruptions, starting with that of mid-April 1981, were predicted between 3 days and 3 weeks in advance. Precursory seismicity, deformation of the crater floor and the lava dome, and, to a lesser extent, gas emissions provided telltale evidence of forthcoming eruptions. The newly developed capability for prediction reduced risk to life and property and influenced land-use decisions.",
    url = "https://doi.org/10.1126/science.221.4618.1369",
    doi = "10.1126/science.221.4618.1369",
    openalex = "W2075123123"
}

The monitoring of gas emissions from Mount St. Helens includes daily airborne measurements of sulfur dioxide in the volcanic plume and monthly sampling of gases from crater fumaroles. The composition of the fumarolic gases has changed slightly since 1980: the water content increased from 90 to 98 percent, and the carbon dioxide concentrations decreased from about 10 to 1 percent. The emission rates of sulfur dioxide and carbon dioxide were at their peak during July and August 1980, decreased rapidly in late 1980, and have remained low and decreased slightly through 1981 and 1982. These patterns suggest steady outgassing of a single batch of magma (with a volume of not less than 0.3 cubic kilometer) to which no significant new magma has been added since mid-1980. The gas data were useful in predicting eruptions in August 1980 and June 1981.

@article{doi101126science22146181383,
    author = "Casadevall, Thomas J. and Rose, William I. and Gerlach, T. M. and Greenland, L.P. and Ewert, John W. and Wunderman, Richard and Symonds, Robert B.",
    title = "Gas Emissions and the Eruptions of Mount St. Helens Through 1982",
    year = "1983",
    journal = "Science",
    abstract = "The monitoring of gas emissions from Mount St. Helens includes daily airborne measurements of sulfur dioxide in the volcanic plume and monthly sampling of gases from crater fumaroles. The composition of the fumarolic gases has changed slightly since 1980: the water content increased from 90 to 98 percent, and the carbon dioxide concentrations decreased from about 10 to 1 percent. The emission rates of sulfur dioxide and carbon dioxide were at their peak during July and August 1980, decreased rapidly in late 1980, and have remained low and decreased slightly through 1981 and 1982. These patterns suggest steady outgassing of a single batch of magma (with a volume of not less than 0.3 cubic kilometer) to which no significant new magma has been added since mid-1980. The gas data were useful in predicting eruptions in August 1980 and June 1981.",
    url = "https://doi.org/10.1126/science.221.4618.1383",
    doi = "10.1126/science.221.4618.1383",
    openalex = "W2093522418"
}

The Mount St. Helens eruptive sequence of 1980 through 1982 reflects the tapping of successively less water-rich, more highly crystallized, and more viscous, highly phyric dacitic magmas. These changes reflect both syn- and preeruption processes. The decreasing water content points to a continued decline in the volume and intensity of explosive pyroclastic activity. This decreasing water content appears to be composed of a long-term trend established during a long period of repose (about 130 years) imposed on short-term trends established during short periods (about 7 to 100 days) of repose between eruptions in the present eruptive cycle. The last two eruptive cycles of this volcano, the T (A.D. 1800) and W cycles (about A. D. 1500), exhibited similar trends. These changes are inferred from a combination of petrographic, bulk chemical, and electron- and ion-microprobe analyses of matrix and melt-inclusion glasses.

@article{doi101126science22146181387,
    author = "Melson, William G.",
    title = "Monitoring the 1980-1982 Eruptions of Mount St. Helens: Compositions and Abundances of Glass",
    year = "1983",
    journal = "Science",
    abstract = "The Mount St. Helens eruptive sequence of 1980 through 1982 reflects the tapping of successively less water-rich, more highly crystallized, and more viscous, highly phyric dacitic magmas. These changes reflect both syn- and preeruption processes. The decreasing water content points to a continued decline in the volume and intensity of explosive pyroclastic activity. This decreasing water content appears to be composed of a long-term trend established during a long period of repose (about 130 years) imposed on short-term trends established during short periods (about 7 to 100 days) of repose between eruptions in the present eruptive cycle. The last two eruptive cycles of this volcano, the T (A.D. 1800) and W cycles (about A. D. 1500), exhibited similar trends. These changes are inferred from a combination of petrographic, bulk chemical, and electron- and ion-microprobe analyses of matrix and melt-inclusion glasses.",
    url = "https://doi.org/10.1126/science.221.4618.1387",
    doi = "10.1126/science.221.4618.1387",
    openalex = "W1969520098"
}

An explosive eruption of Mount St. Helens on 19 March 1982 had substantial impact beyond the vent because hot eruption products interacted with a thick snowpack. A blast of hot pumice, dome rocks, and gas dislodged crater-wall snow that avalanched through the crater and down the north flank. Snow in the crater swiftly melted to form a transient lake, from which a destructive flood and lahar swept down the north flank and the North Fork Toutle River.

@article{doi101126science22146181394,
    author = "Waitt, Richard B. and Pierson, Thomas C. and MacLeod, N. S. and Janda, Richard J. and Voight, B. and Holcomb, Robin T.",
    title = "Eruption-Triggered Avalanche, Flood, and Lahar at Mount St. Helens—Effects of Winter Snowpack",
    year = "1983",
    journal = "Science",
    abstract = "An explosive eruption of Mount St. Helens on 19 March 1982 had substantial impact beyond the vent because hot eruption products interacted with a thick snowpack. A blast of hot pumice, dome rocks, and gas dislodged crater-wall snow that avalanched through the crater and down the north flank. Snow in the crater swiftly melted to form a transient lake, from which a destructive flood and lahar swept down the north flank and the North Fork Toutle River.",
    url = "https://doi.org/10.1126/science.221.4618.1394",
    doi = "10.1126/science.221.4618.1394",
    openalex = "W1974964313"
}

This report identifies volcanoes in the Cascade Range of Washington, Oregon, and California that constitute a potential threat to people and works of man, and assesses the hazards that could result from future eruptions of these volcanoes. The assessments are based on the premise that past eruptive histories of volcanoes provide the best basis for judging the most likely kinds, frequencies, and magnitudes of future volcanic events. These assessments can be used to evaluate volcanic hazards at sites of proposed nuclear power plants, as well as for more general purposes of long-range land-use planning. The principal conclusions of the report include the following.

@article{doi103133ofr87297,
    author = "Hoblitt, Richard P. and Miller, C. Dan and Scott, William E.",
    title = "Volcanic hazards with regard to siting nuclear-power plants in the Pacific Northwest",
    year = "1987",
    journal = "Antarctica A Keystone in a Changing World",
    abstract = "This report identifies volcanoes in the Cascade Range of Washington, Oregon, and California that constitute a potential threat to people and works of man, and assesses the hazards that could result from future eruptions of these volcanoes. The assessments are based on the premise that past eruptive histories of volcanoes provide the best basis for judging the most likely kinds, frequencies, and magnitudes of future volcanic events. These assessments can be used to evaluate volcanic hazards at sites of proposed nuclear power plants, as well as for more general purposes of long-range land-use planning. The principal conclusions of the report include the following.",
    url = "https://doi.org/10.3133/ofr87297",
    doi = "10.3133/ofr87297",
    openalex = "W2106745059"
}

@misc{crossref1989potential,
    title = "Potential hazards from future volcanic eruptions in California",
    year = "1989",
    url = "https://doi.org/10.3133/b1847",
    doi = "10.3133/b1847",
    openalex = "W1536218017",
    references = "doi1010160012821x67900568, doi1010160264370785900353, doi1010160377027378900239, doi1010160377027385900794, doi101029jb081i005p00725, doi101029jb085ib05p02381, doi101126science1213145481, doi10113000167606196980157amoucs20co2, doi10113000167606197384663ssibdw20co2, openalexw1973279175"
}

At the beginning of the twentieth century, volcanology began to emerge as a modern science as a result of increased interest in eruptive phenomena following some of the worst volcanic disasters in recorded history: Krakatau (Indonesia) in 1883 and Mont Pelée (Martinique), Soufrière (St. Vincent), and Santa María (Guatemala) in 1902. Volcanology is again experiencing a period of heightened public awareness and scientific growth in the 1980s, the worst period since 1902 in terms of volcanic disasters and crises. A review of hazards mitigation approaches and techniques indicates that significant advances have been made in hazards assessment, volcano monitoring, and eruption forecasting. For example, the remarkable accuracy of the predictions of dome‐building events at Mount St. Helens since June 1980 is unprecedented. Yet a predictive capability for more voluminous and explosive eruptions still has not been achieved. Studies of magma‐induced seismicity and ground deformation continue to provide the most systematic and reliable data for early detection of precursors to eruptions and shallow intrusions. In addition, some other geophysical monitoring techniques and geochemical methods have been refined and are being more widely applied and tested. Comparison of the four major volcanic disasters of the 1980s (Mount St. Helens, U.S.A. (1980), El Chichón, Mexico (1982); Galunggung, Indonesia (1982); and Nevado del Ruíz, Colombia (1985) illustrates the importance of predisaster geoscience studies, volcanic hazards assessments, volcano monitoring, contingency planning, and effective communications between scientists and authorities. The death toll (>22,000) from the Ruíz catastrophe probably could have been greatly reduced; the reasons for the tragically ineffective implementation of evacuation measures are still unclear and puzzling in view of the fact that sufficient warnings were given. The most pressing problem in the mitigation of volcanic and associated hazards on a global scale is that most of the world's dangerous volcanoes are in densely populated countries that lack the economic and scientific resources or the political will to adequately study and monitor them. This problem afflicts both developed and developing countries, but it is especially acute for the latter. The greatest advances in volcanic hazards mitigation in the near future are most likely to be achieved by wider application of existing technology to poorly understood and studied volcanoes, rather than by refinements or new discoveries in technology alone.

@article{doi101029rg027i002p00237,
    author = "Tilling, Robert I.",
    title = "Volcanic hazards and their mitigation: Progress and problems",
    year = "1989",
    journal = "Reviews of Geophysics",
    abstract = "At the beginning of the twentieth century, volcanology began to emerge as a modern science as a result of increased interest in eruptive phenomena following some of the worst volcanic disasters in recorded history: Krakatau (Indonesia) in 1883 and Mont Pelée (Martinique), Soufrière (St. Vincent), and Santa María (Guatemala) in 1902. Volcanology is again experiencing a period of heightened public awareness and scientific growth in the 1980s, the worst period since 1902 in terms of volcanic disasters and crises. A review of hazards mitigation approaches and techniques indicates that significant advances have been made in hazards assessment, volcano monitoring, and eruption forecasting. For example, the remarkable accuracy of the predictions of dome‐building events at Mount St. Helens since June 1980 is unprecedented. Yet a predictive capability for more voluminous and explosive eruptions still has not been achieved. Studies of magma‐induced seismicity and ground deformation continue to provide the most systematic and reliable data for early detection of precursors to eruptions and shallow intrusions. In addition, some other geophysical monitoring techniques and geochemical methods have been refined and are being more widely applied and tested. Comparison of the four major volcanic disasters of the 1980s (Mount St. Helens, U.S.A. (1980), El Chichón, Mexico (1982); Galunggung, Indonesia (1982); and Nevado del Ruíz, Colombia (1985) illustrates the importance of predisaster geoscience studies, volcanic hazards assessments, volcano monitoring, contingency planning, and effective communications between scientists and authorities. The death toll (>22,000) from the Ruíz catastrophe probably could have been greatly reduced; the reasons for the tragically ineffective implementation of evacuation measures are still unclear and puzzling in view of the fact that sufficient warnings were given. The most pressing problem in the mitigation of volcanic and associated hazards on a global scale is that most of the world's dangerous volcanoes are in densely populated countries that lack the economic and scientific resources or the political will to adequately study and monitor them. This problem afflicts both developed and developing countries, but it is especially acute for the latter. The greatest advances in volcanic hazards mitigation in the near future are most likely to be achieved by wider application of existing technology to poorly understood and studied volcanoes, rather than by refinements or new discoveries in technology alone.",
    url = "https://doi.org/10.1029/rg027i002p00237",
    doi = "10.1029/rg027i002p00237",
    openalex = "W2044735005",
    references = "crossref1978potential, doi1010160264370785900444, doi101029rg024i003p00579, doi101029sc001p0001, doi101029sc001p0025, doi101029sc001p0051"
}

@article{doi101007bf00278003,
    author = "Pallister, John S. and Hoblitt, Richard P. and Crandell, Dwight Raymond and Mullineaux, Donal Ray",
    title = "Mount St. Helens a decade after the 1980 eruptions: magmatic models, chemical cycles, and a revised hazards assessment",
    year = "1992",
    journal = "Bulletin of Volcanology",
    url = "https://doi.org/10.1007/bf00278003",
    doi = "10.1007/bf00278003",
    openalex = "W2088019799",
    references = "crandell1987deposits, crossref1980recent, doi1010079789401578059, doi1010160016703784904150, doi1010160040195168900590, doi1010160377027377900129, doi101029jb089ib07p06309, doi101029jb090ib04p02929, doi101029jb091ib05p04920, doi101093petrology285781, doi102113gsecongeo686799, doi103133pp1444, openalexw597459718"
}

We describe an event tree scheme to quantitatively estimate both long‐ and short‐term volcanic hazard. The procedure is based on a Bayesian approach that produces a probability estimation of any possible event in which we are interested and can make use of all available information including theoretical models, historical and geological data, and monitoring observations. The main steps in the procedure are (1) to estimate an a priori probability distribution based upon theoretical knowledge, (2) to modify that using past data, and (3) to modify it further using current monitoring data. The scheme allows epistemic and aleatoric uncertainties to be dealt with in a formal way, through estimation of probability distributions at each node of the event tree. We then describe an application of the method to the case of Mount Vesuvius. Although the primary intent of the example is to illustrate the methodology, one result of this application merits special mention. The present emergency response plan for Mount Vesuvius is referenced to a maximum expected event (MEE), the largest out of all the possible eruptions within the next few decades. Our calculation suggest that there is a nonnegligible (1–20%) chance that the next eruption could be larger than that stipulated in the present MEE. The methodology allows all assumptions and thresholds to be clearly identified and provides a rational means for their revision if new data or information are obtained.

@article{doi1010292004jb003155,
    author = "Marzocchi, Warner and Sandri, Laura and Gasparini, Paolo and Newhall, Christopher G. and Boschi, E.",
    title = "Quantifying probabilities of volcanic events: The example of volcanic hazard at Mount Vesuvius",
    year = "2004",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "We describe an event tree scheme to quantitatively estimate both long‐ and short‐term volcanic hazard. The procedure is based on a Bayesian approach that produces a probability estimation of any possible event in which we are interested and can make use of all available information including theoretical models, historical and geological data, and monitoring observations. The main steps in the procedure are (1) to estimate an a priori probability distribution based upon theoretical knowledge, (2) to modify that using past data, and (3) to modify it further using current monitoring data. The scheme allows epistemic and aleatoric uncertainties to be dealt with in a formal way, through estimation of probability distributions at each node of the event tree. We then describe an application of the method to the case of Mount Vesuvius. Although the primary intent of the example is to illustrate the methodology, one result of this application merits special mention. The present emergency response plan for Mount Vesuvius is referenced to a maximum expected event (MEE), the largest out of all the possible eruptions within the next few decades. Our calculation suggest that there is a nonnegligible (1–20\%) chance that the next eruption could be larger than that stipulated in the present MEE. The methodology allows all assumptions and thresholds to be clearly identified and provides a rational means for their revision if new data or information are obtained.",
    url = "https://doi.org/10.1029/2004jb003155",
    doi = "10.1029/2004jb003155",
    openalex = "W1492080396"
}

A dome-building eruption at Mount Hood, Oregon, starting in A.D. 1780 and lasting until ca. 1793, produced dome-collapse lithic pyroclastic flows that triggered lahars and intermittently fed 10 8 m 3 of coarse volcaniclastic sediment to sediment reservoirs in headwater canyons of the Sandy River. Mobilization of dominantly sandy sediment from these reservoirs by lahars and seasonal floods initiated downstream migration of a sediment wave that resulted in a profound cycle of aggradation and degradation in the lowermost reach of the river (depositional reach), 61–87 km from the source. Stratigraphic and sedimentologic relations in the alluvial fill, together with dendrochronologic dating of degradation terraces, demonstrate that (1) channel aggradation in response to sediment loading in the headwater canyons raised the river bed in this reach at least 23 m in a decade or less; (2) the transition from aggradation to degradation in the upper part of this reach roughly coincided with the end of the dome-building eruption; (3) fluvial sediment transport and deposition, augmented by one lahar, achieved a minimum average aggradation rate of ∼2 m/yr; (4) the degradation phase of the cycle was more prolonged than the aggradation phase, requiring more than half a century for the river to reach its present bed elevation; and (5) the present longitudinal profile of the Sandy River in this reach is at least 3 m above the pre-eruption profile. The pattern and rate of channel response and recovery in the Sandy River following heavy sediment loading resemble those of other rivers similarly subjected to very large sediment inputs. The magnitude of channel aggradation in the lower Sandy River, greater than that achieved at other volcanoes following much larger eruptions, was likely enhanced by lateral confinement of the channel within a narrow incised valley. A combination of at least one lahar and winter floods from frequent moderate-magnitude rainstorms and infrequent very large storms was responsible for flushing large volumes of sediment to the depositional reach. These conditions permitted a sedimentation response in the Sandy River that approached the magnitude of channel aggradation resulting elsewhere from large explosive eruptions and high-intensity rainfall regimes, despite the fact that the Sandy River aggradation was in response to an unremarkable dome-building eruption in a climate dominated by low to moderate rainfall intensities.

@article{doi101130b301271,
    author = "Pierson, Thomas C. and Pringle, Patrick T. and Cameron, Karen A.",
    title = "Magnitude and timing of downstream channel aggradation and degradation in response to a dome-building eruption at Mount Hood, Oregon",
    year = "2010",
    journal = "Geological Society of America Bulletin",
    abstract = "A dome-building eruption at Mount Hood, Oregon, starting in A.D. 1780 and lasting until ca. 1793, produced dome-collapse lithic pyroclastic flows that triggered lahars and intermittently fed 10 8 m 3 of coarse volcaniclastic sediment to sediment reservoirs in headwater canyons of the Sandy River. Mobilization of dominantly sandy sediment from these reservoirs by lahars and seasonal floods initiated downstream migration of a sediment wave that resulted in a profound cycle of aggradation and degradation in the lowermost reach of the river (depositional reach), 61–87 km from the source. Stratigraphic and sedimentologic relations in the alluvial fill, together with dendrochronologic dating of degradation terraces, demonstrate that (1) channel aggradation in response to sediment loading in the headwater canyons raised the river bed in this reach at least 23 m in a decade or less; (2) the transition from aggradation to degradation in the upper part of this reach roughly coincided with the end of the dome-building eruption; (3) fluvial sediment transport and deposition, augmented by one lahar, achieved a minimum average aggradation rate of ∼2 m/yr; (4) the degradation phase of the cycle was more prolonged than the aggradation phase, requiring more than half a century for the river to reach its present bed elevation; and (5) the present longitudinal profile of the Sandy River in this reach is at least 3 m above the pre-eruption profile. The pattern and rate of channel response and recovery in the Sandy River following heavy sediment loading resemble those of other rivers similarly subjected to very large sediment inputs. The magnitude of channel aggradation in the lower Sandy River, greater than that achieved at other volcanoes following much larger eruptions, was likely enhanced by lateral confinement of the channel within a narrow incised valley. A combination of at least one lahar and winter floods from frequent moderate-magnitude rainstorms and infrequent very large storms was responsible for flushing large volumes of sediment to the depositional reach. These conditions permitted a sedimentation response in the Sandy River that approached the magnitude of channel aggradation resulting elsewhere from large explosive eruptions and high-intensity rainfall regimes, despite the fact that the Sandy River aggradation was in response to an unremarkable dome-building eruption in a climate dominated by low to moderate rainfall intensities.",
    url = "https://doi.org/10.1130/b30127.1",
    doi = "10.1130/b30127.1",
    openalex = "W2028450370",
    references = "crossref1980recent"
}

As the number of people living at risk from volcanic hazards in the U.S. Pacific Northwest grows, more detailed studies of household preparedness in at-risk communities are needed to develop effective mitigation, response, and recovery plans. This study examines two aspects of preparedness behavior motivation in the Skagit Valley (WA), which is at risk from Mount Baker and Glacier Peak lahars. First, we examine the influence of perceived response-efficacy, protective response costs, self-efficacy, and ascription of responsibility on preparedness. Results indicate few respondents believe high perceived protective response costs, low perceived response-efficacy, or low perceived protection responsibility prevent them from adopting frequently recommended preparedness behaviors. Correlations with preparedness suggest perceived self-efficacy and ascription of responsibility play a more dominant role in determining preparedness behaviors, albeit a less readily recognized role. Second, we investigate how participation in hazard management at a professional level (e.g., working as a first responder or leader within the local city government, hospitals, school districts, Red Cross, or utilities, transportation, or water companies) influences knowledge, risk perception, and household preparedness. Results show that professional participation minimally influences household preparedness, but successfully improves perceived self-efficacy, confidence in officials, and information seeking behavior. Given these results, we argue (1) for inclusion of ascription of responsibility variables in studies of preparedness behavior motivation and (2) that specific types of participation in response-related activities (e.g., public, professional, specific training programs) may affect household preparedness differently, whereas self-efficacy and confidence in officials may improve regardless of participation type because of increased interaction with emergency officials.

@article{doi101186s1361701700558,
    author = "Corwin, Kimberley A. and Brand, Brittany D. and Hubbard, Monica L. and Johnston, David",
    title = "Household preparedness motivation in lahar hazard zones: assessing the adoption of preparedness behaviors among laypeople and response professionals in communities downstream from Mount Baker and Glacier Peak (USA) volcanoes",
    year = "2017",
    journal = "Journal of Applied Volcanology",
    abstract = "As the number of people living at risk from volcanic hazards in the U.S. Pacific Northwest grows, more detailed studies of household preparedness in at-risk communities are needed to develop effective mitigation, response, and recovery plans. This study examines two aspects of preparedness behavior motivation in the Skagit Valley (WA), which is at risk from Mount Baker and Glacier Peak lahars. First, we examine the influence of perceived response-efficacy, protective response costs, self-efficacy, and ascription of responsibility on preparedness. Results indicate few respondents believe high perceived protective response costs, low perceived response-efficacy, or low perceived protection responsibility prevent them from adopting frequently recommended preparedness behaviors. Correlations with preparedness suggest perceived self-efficacy and ascription of responsibility play a more dominant role in determining preparedness behaviors, albeit a less readily recognized role. Second, we investigate how participation in hazard management at a professional level (e.g., working as a first responder or leader within the local city government, hospitals, school districts, Red Cross, or utilities, transportation, or water companies) influences knowledge, risk perception, and household preparedness. Results show that professional participation minimally influences household preparedness, but successfully improves perceived self-efficacy, confidence in officials, and information seeking behavior. Given these results, we argue (1) for inclusion of ascription of responsibility variables in studies of preparedness behavior motivation and (2) that specific types of participation in response-related activities (e.g., public, professional, specific training programs) may affect household preparedness differently, whereas self-efficacy and confidence in officials may improve regardless of participation type because of increased interaction with emergency officials.",
    url = "https://doi.org/10.1186/s13617-017-0055-8",
    doi = "10.1186/s13617-017-0055-8",
    openalex = "W2583153425",
    references = "hyde1978postglacial"
}

The California volcano locations, threat rank and hazard zones data release contains two shapefiles for download or use as a web map service. The California Volcanic Center Locations shapefile was created to provide a generalized location of volcano hazard sources. The California Volcano Hazard Zones shapefile was created from previously published hazard zone reports. Specific details about each file can be found in the metadata included with each file and the read-me document for this data release. Together, these files were used to define California Volcano Hazards for the GIS analysis that supports conclusions in the California's exposure to volcano hazards report. Geologists produce hazard zone maps to convey the types of hazards that may occur during future eruptions and to identify the areas of potential impact. Hazard zones are derived from detailed geologic studies that identify the type and extent of volcanic deposits created in past eruptions and on isotopic and paleomagnetic dating of the age and frequency of eruptions. Users of the information in this report should be aware that volcanic areas in California are the subject of continuing research and that refinement of volcano hazard zones are sure to come in subsequent years. The volcano hazard zones provided in this report reflect a simplified compilation of the following peer-reviewed U.S. Geological Survey reports: 1) For Lassen Volcanic Center: Clynne, M.A., Robinson, J.E., Nathenson, M., and Muffler, L.J.P., 2012, Volcano hazards assessment for the Lassen region, northern California: U.S. Geological Survey Scientific Investigations Report 2012-5176-A, 47 p., 1 plate, scale 1:200,000, [Available at http://pubs.usgs.gov/sir/2012/5176/a], and, Robinson, J.E., Clynne, M.A., 2012, Lahar hazard zones for eruption-generated lahars in the Lassen Volcanic Center, California: U.S. Geological Survey Scientific Investigations Report 2012-5176-C, [Available at http://pubs.usgs.gov/sir/2012/5176/c]. 2) For Medicine Lake Volcano: Donnelly-Nolan, J.M, Nathenson, M., Champion, D.E., Ramsey, D.W., Lowenstern, J.B., and Ewert, J.W., 2007, Volcano hazards assessment for Medicine Lake volcano, northern California: U.S. Geological Scientific Investigations Report 2007-5174-A, 33 p., 1 plate, [Available at https://pubs.usgs.gov/sir/2007/5174/a, and, subsequent GIS compilation in Ramsey, D.W., Donnelly-Nolan, J.M., and Robinson, J.E., 2019, Hazard boundaries for the volcanic hazard assessment of Medicine Lake volcano, California: U.S. Geological Survey data release, available at https://doi.org/10.5066/P9SDH8E6.] 3) For Mount Shasta, Clear Lake volcanic field, Long Valley volcanic field, Ubehebe Craters, Salton Buttes: Miller, C.D., 1989, Potential hazards from future volcanic eruptions in California: U.S. Geological Survey Bulletin 1847, 17 p., 2 tables, 1 plate, scale 1:500,000. [Available at https://pubs.usgs.gov/bul/1847, and, subsequent GIS compilation in White, M.N., Ramsey, D.W., and Miller, C.D., 2011, Database for potential hazards from future volcanic eruptions in California: U.S. Geological Survey Data Series 661 (database for Bulletin 1847), available at http://pubs.usgs.gov/ds/661]. The studies above represent the work of numerous researchers occurring over a collective span of almost three decades. As a result, methodology, nomenclature, and level of geologic detail vary from one report to the next. The simplified hazard zone maps presented in this report maintain the scientific integrity of the reports listed above, while simplifying nomenclature and amalgamating information to provide a consistent, statewide portrayal of California's volcano hazard zones. It is important to note that volcanic hazard zone boundaries are gradational in nature, with the severity of the hazard diminishing outward from the eruption site (vent), or, for the various flowage hazards, with increasing height above valley floors or basins. The simplified hazard zone maps in this report portray hazard boundaries as diffuse bands rather than as sharp lines. Diffuse boundaries give a qualitative sense of the level of uncertainty in the original data, and account for differences in geologic resolution (map scales) across the various published reports listed above. It is unlikely that all parts of a volcanic area will be impacted during an eruption. As a volcano reawakens, real-time monitoring of earthquakes, ground deformation, and gas emissions will provide the information needed to anticipate the vent location and geographic sectors most likely to be impacted. Specific hazards to people and property will depend on the eruption style, the volume of lava erupted, the location of the eruptive vent, and the eruption duration, as well as local meteorological and hydrological conditions.

@misc{peters2019california,
    author = "Peters, Jeff and Mangan, Margaret T and Ball, Jessica L and Wood, Nathan J and Jones, Jamie L and Abdollahian, Nina",
    title = "California volcano locations, threat rank and hazard zones",
    year = "2019",
    publisher = "U.S. Geological Survey",
    abstract = "The California volcano locations, threat rank and hazard zones data release contains two shapefiles for download or use as a web map service. The California Volcanic Center Locations shapefile was created to provide a generalized location of volcano hazard sources. The California Volcano Hazard Zones shapefile was created from previously published hazard zone reports. Specific details about each file can be found in the metadata included with each file and the read-me document for this data release. Together, these files were used to define California Volcano Hazards for the GIS analysis that supports conclusions in the California's exposure to volcano hazards report. Geologists produce hazard zone maps to convey the types of hazards that may occur during future eruptions and to identify the areas of potential impact. Hazard zones are derived from detailed geologic studies that identify the type and extent of volcanic deposits created in past eruptions and on isotopic and paleomagnetic dating of the age and frequency of eruptions. Users of the information in this report should be aware that volcanic areas in California are the subject of continuing research and that refinement of volcano hazard zones are sure to come in subsequent years. The volcano hazard zones provided in this report reflect a simplified compilation of the following peer-reviewed U.S. Geological Survey reports: 1) For Lassen Volcanic Center: Clynne, M.A., Robinson, J.E., Nathenson, M., and Muffler, L.J.P., 2012, Volcano hazards assessment for the Lassen region, northern California: U.S. Geological Survey Scientific Investigations Report 2012-5176-A, 47 p., 1 plate, scale 1:200,000, [Available at http://pubs.usgs.gov/sir/2012/5176/a], and, Robinson, J.E., Clynne, M.A., 2012, Lahar hazard zones for eruption-generated lahars in the Lassen Volcanic Center, California: U.S. Geological Survey Scientific Investigations Report 2012-5176-C, [Available at http://pubs.usgs.gov/sir/2012/5176/c]. 2) For Medicine Lake Volcano: Donnelly-Nolan, J.M, Nathenson, M., Champion, D.E., Ramsey, D.W., Lowenstern, J.B., and Ewert, J.W., 2007, Volcano hazards assessment for Medicine Lake volcano, northern California: U.S. Geological Scientific Investigations Report 2007-5174-A, 33 p., 1 plate, [Available at https://pubs.usgs.gov/sir/2007/5174/a, and, subsequent GIS compilation in Ramsey, D.W., Donnelly-Nolan, J.M., and Robinson, J.E., 2019, Hazard boundaries for the volcanic hazard assessment of Medicine Lake volcano, California: U.S. Geological Survey data release, available at https://doi.org/10.5066/P9SDH8E6.] 3) For Mount Shasta, Clear Lake volcanic field, Long Valley volcanic field, Ubehebe Craters, Salton Buttes: Miller, C.D., 1989, Potential hazards from future volcanic eruptions in California: U.S. Geological Survey Bulletin 1847, 17 p., 2 tables, 1 plate, scale 1:500,000. [Available at https://pubs.usgs.gov/bul/1847, and, subsequent GIS compilation in White, M.N., Ramsey, D.W., and Miller, C.D., 2011, Database for potential hazards from future volcanic eruptions in California: U.S. Geological Survey Data Series 661 (database for Bulletin 1847), available at http://pubs.usgs.gov/ds/661]. The studies above represent the work of numerous researchers occurring over a collective span of almost three decades. As a result, methodology, nomenclature, and level of geologic detail vary from one report to the next. The simplified hazard zone maps presented in this report maintain the scientific integrity of the reports listed above, while simplifying nomenclature and amalgamating information to provide a consistent, statewide portrayal of California's volcano hazard zones. It is important to note that volcanic hazard zone boundaries are gradational in nature, with the severity of the hazard diminishing outward from the eruption site (vent), or, for the various flowage hazards, with increasing height above valley floors or basins. The simplified hazard zone maps in this report portray hazard boundaries as diffuse bands rather than as sharp lines. Diffuse boundaries give a qualitative sense of the level of uncertainty in the original data, and account for differences in geologic resolution (map scales) across the various published reports listed above. It is unlikely that all parts of a volcanic area will be impacted during an eruption. As a volcano reawakens, real-time monitoring of earthquakes, ground deformation, and gas emissions will provide the information needed to anticipate the vent location and geographic sectors most likely to be impacted. Specific hazards to people and property will depend on the eruption style, the volume of lava erupted, the location of the eruptive vent, and the eruption duration, as well as local meteorological and hydrological conditions.",
    url = "https://www.sciencebase.gov/catalog/item/5c926253e4b0938824572a72",
    doi = "10.5066/p9xt483z"
}

The rigorous assessment of volcanic hazards relies on setting contemporary monitoring observations within an accurate, longer-term geological context. Revealing that geological context requires the detailed fieldwork, mapping and laboratory analysis of the erupted materials. However, many of the world’s most dangerous volcanic systems are located on or near coasts (e.g., the Phlegraean Fields and Vesuvius in Italy), islands (e.g., the volcanic archipelagos of the Pacific, south-east Asia, and Eastern Caribbean), or underwater (e.g., the recently erupting Hunga Tonga–Hunga Ha’apai volcano), meaning that much of their erupted material is deposited on the sea bed. The only way to sample this material directly is with seafloor sediment cores. This perspectives paper outlines how marine sediment cores are a vital yet underused resource for assessing volcanic hazards by: (1) outlining the spatio-temporal scope of the marine volcanic record and its main deposit types, (2) providing existing examples where marine sediments have contributed to volcanic hazard assessments; (3) highlighting the Sunda Arc, Indonesia as an example location where marine sediment cores are yet to contribute to hazard assessments, and (4) proposing that marine sediment cores can contribute to our understanding of very large eruptions that have a global impact. Overall, this perspectives paper aims to promote the utility of marine sediment cores in future volcanic hazard assessments, while also providing some basic information to assist researchers who are considering integrating marine sediment cores into their volcanological research.

@article{doi103390geosciences13040124,
    author = "Satow, Chris and Watt, Sebastian and Cassidy, Michael and Pyle, David M. and Deng, Yuqiao Natalie",
    title = "The Contributions of Marine Sediment Cores to Volcanic Hazard Assessments: Present Examples and Future Perspectives",
    year = "2023",
    journal = "Geosciences",
    abstract = "The rigorous assessment of volcanic hazards relies on setting contemporary monitoring observations within an accurate, longer-term geological context. Revealing that geological context requires the detailed fieldwork, mapping and laboratory analysis of the erupted materials. However, many of the world’s most dangerous volcanic systems are located on or near coasts (e.g., the Phlegraean Fields and Vesuvius in Italy), islands (e.g., the volcanic archipelagos of the Pacific, south-east Asia, and Eastern Caribbean), or underwater (e.g., the recently erupting Hunga Tonga–Hunga Ha’apai volcano), meaning that much of their erupted material is deposited on the sea bed. The only way to sample this material directly is with seafloor sediment cores. This perspectives paper outlines how marine sediment cores are a vital yet underused resource for assessing volcanic hazards by: (1) outlining the spatio-temporal scope of the marine volcanic record and its main deposit types, (2) providing existing examples where marine sediments have contributed to volcanic hazard assessments; (3) highlighting the Sunda Arc, Indonesia as an example location where marine sediment cores are yet to contribute to hazard assessments, and (4) proposing that marine sediment cores can contribute to our understanding of very large eruptions that have a global impact. Overall, this perspectives paper aims to promote the utility of marine sediment cores in future volcanic hazard assessments, while also providing some basic information to assist researchers who are considering integrating marine sediment cores into their volcanological research.",
    url = "https://doi.org/10.3390/geosciences13040124",
    doi = "10.3390/geosciences13040124",
    openalex = "W4366774195",
    references = "doi101016jjvolgeores200908007"
}

Previous efforts to characterize lahar threats posed to communities downstream of volcanoes have focused primarily on delineating hazard zones that lack information on lahar-arrival times and exposure estimates that implicitly treat threats to be the same regardless of distance from the volcano. Estimated lahar-arrival times, travel times for individuals to leave hazard zones, and possible evacuation delays related to event identification, warning dissemination, and evacuee behavior are important, but often overlooked, aspects of understanding the societal threats posed by lahars. These temporal considerations are especially important for unexpected lahars that could occur due to slope failure in the absence of precursory volcanic unrest or eruption. This case study examines the role of time in lahar evacuations by quantifying population exposure and evacuation potential for non-eruptive lahar hazards associated with Mount Rainier, Washington. Lahars could directly affect tens of thousands of residents and employees, thousands of students at primary and secondary schools, and hundreds of individuals at long-term residential care facilities. Geospatial path-distance modeling quantified evacuation potential for 736 scenarios that represent combinations of lahar sources, evacuation destinations, pedestrian travel speeds, and a range of departure-delay assumptions. Depending on location, some communities may have substantial loss of life in tens of minutes after lahar initiation, whereas other communities may be managing large-scale evacuations over several hours. Estimates of evacuation success based on a range of scenarios provide individuals in hazard zones and risk-reduction agencies with insights on how their actions may increase or decrease the number of people that survive future lahars.

@article{doi101016jijdrr2026106132,
    author = "Wood, Nathan and Peters, Jeff",
    title = "Influence of modeling assumptions on pedestrian evacuation success for non-eruptive lahar hazards at Mount Rainier, Washington",
    year = "2026",
    journal = "International Journal of Disaster Risk Reduction",
    abstract = "Previous efforts to characterize lahar threats posed to communities downstream of volcanoes have focused primarily on delineating hazard zones that lack information on lahar-arrival times and exposure estimates that implicitly treat threats to be the same regardless of distance from the volcano. Estimated lahar-arrival times, travel times for individuals to leave hazard zones, and possible evacuation delays related to event identification, warning dissemination, and evacuee behavior are important, but often overlooked, aspects of understanding the societal threats posed by lahars. These temporal considerations are especially important for unexpected lahars that could occur due to slope failure in the absence of precursory volcanic unrest or eruption. This case study examines the role of time in lahar evacuations by quantifying population exposure and evacuation potential for non-eruptive lahar hazards associated with Mount Rainier, Washington. Lahars could directly affect tens of thousands of residents and employees, thousands of students at primary and secondary schools, and hundreds of individuals at long-term residential care facilities. Geospatial path-distance modeling quantified evacuation potential for 736 scenarios that represent combinations of lahar sources, evacuation destinations, pedestrian travel speeds, and a range of departure-delay assumptions. Depending on location, some communities may have substantial loss of life in tens of minutes after lahar initiation, whereas other communities may be managing large-scale evacuations over several hours. Estimates of evacuation success based on a range of scenarios provide individuals in hazard zones and risk-reduction agencies with insights on how their actions may increase or decrease the number of people that survive future lahars.",
    url = "https://doi.org/10.1016/j.ijdrr.2026.106132",
    doi = "10.1016/j.ijdrr.2026.106132",
    openalex = "W7148829674",
    references = "doi101186s1361702400142z"
}