Pacific northwest

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{crandell1975mount,
    author = "Crandell, Dwight R. and Mullineaux, Donal R. 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",
    number = "4175",
    pages = "438-441",
    volume = "187"
}

@article{hoblitt1980mount,
    author = "Hoblitt, Richard P. and Crandell, Dwight R. and Mullineaux, Donal R.",
    title = "Mount St. Helens eruptive behavior during the past 1,500 yr",
    year = "1980",
    journal = "Geology",
    url = "https://doi.org/10.1130/0091-7613(1980)8<555:mshebd>2.0.co;2",
    doi = "10.1130/0091-7613(1980)8<555:mshebd>2.0.co;2",
    number = "11",
    pages = "555",
    volume = "8"
}

@misc{hoblitt1980mount1,
    author = "Hoblitt, R. P. and Crandell, D. R. and Millineaux, D. R",
    title = "Mount St. Helens eruptive behavior during the parst 1,500 years",
    year = "1980",
    howpublished = "Geology, v. 8, p. 555-559",
    note = "talkorigins\_source = {true}; raw\_reference = {Hoblitt, R. P., Crandell, D. R., and Millineaux, D. R., 1980, Mount St. Helens eruptive behavior during the parst 1,500 years: Geology, v. 8, p. 555-559.}"
}

New material from the dacite lava dome of Mount St. Helens, collected soon after the start of each successive extrusion, is subjected to rapid chemical and petrologic analysis. The crystallinity of the dacite lava produced in 1981 and 1982 is 38 to 42 percent, about 10 percent higher than for products of the explosive 1980 eruptions. This increase in crystallinity accompanies a decrease in the ratio of hornblende to hornblende plus orthopyroxene, which suggests that the volatile-rich, crystal-poor material explosively erupted in 1980 came from the top of a zoned magma chamber and that a lower, volatile-poor and crystal-rich region is now being tapped. The major-element chemistry of the dacite lava has remained essentially constant (62 to 63 percent silica) since August 1980, ending a trend of decreasing silica seen in the products of the explosive eruptions of May through August 1980.

@article{cashman1983petrologic,
    author = "Cashman, Katharine V. and Taggart, Joseph E.",
    title = "Petrologic Monitoring of 1981 and 1982 Eruptive Products from Mount St. Helens",
    year = "1983",
    journal = "Science",
    abstract = "New material from the dacite lava dome of Mount St. Helens, collected soon after the start of each successive extrusion, is subjected to rapid chemical and petrologic analysis. The crystallinity of the dacite lava produced in 1981 and 1982 is 38 to 42 percent, about 10 percent higher than for products of the explosive 1980 eruptions. This increase in crystallinity accompanies a decrease in the ratio of hornblende to hornblende plus orthopyroxene, which suggests that the volatile-rich, crystal-poor material explosively erupted in 1980 came from the top of a zoned magma chamber and that a lower, volatile-poor and crystal-rich region is now being tapped. The major-element chemistry of the dacite lava has remained essentially constant (62 to 63 percent silica) since August 1980, ending a trend of decreasing silica seen in the products of the explosive eruptions of May through August 1980.",
    url = "https://doi.org/10.1126/science.221.4618.1385",
    doi = "10.1126/science.221.4618.1385",
    number = "4618",
    pages = "1385-1387",
    volume = "221"
}

@article{sweet1983mount,
    author = "SWEET, H. R. and EDWARDS, J. E.",
    title = "Mount St. Helens Eruptive Impacts to the Toutle Community Ground-Water Supply",
    year = "1983",
    journal = "Environmental \& Engineering Geoscience",
    url = "https://doi.org/10.2113/gseegeosci.xx.2.145",
    doi = "10.2113/gseegeosci.xx.2.145",
    number = "2",
    pages = "145-150",
    volume = "xx"
}

@article{swanson1985forecasts,
    author = "Swanson, D.A. and Casadevall, T.J. and Dzurisin, D. and Holcomb, R.T. and Newhall, C.G. and Malone, S.D. and Weaver, C.S.",
    title = "Forecasts and predictions of eruptive activity at Mount St. Helens, USA: 1975–1984",
    year = "1985",
    journal = "Journal of Geodynamics",
    url = "https://doi.org/10.1016/0264-3707(85)90044-4",
    doi = "10.1016/0264-3707(85)90044-4",
    number = "3-4",
    pages = "397-423",
    volume = "3"
}

@article{gardner1995influence,
    author = "Gardner, James E. and Carey, Steve and Sigurdsson, Haraldur and Rutherford, Malcolm J.",
    title = "Influence of magma composition on the eruptive activity of Mount St. Helens, Washington",
    year = "1995",
    journal = "Geology",
    url = "https://doi.org/10.1130/0091-7613(1995)023<0523:iomcot>2.3.co;2",
    doi = "10.1130/0091-7613(1995)023<0523:iomcot>2.3.co;2",
    number = "6",
    pages = "523",
    volume = "23"
}

@misc{clynne2005pre1980,
    author = "Clynne, Michael A. and Ramsey, David W. and Wolfe, Edward W. and Hendley, James W. and Stauffer, Peter H.",
    title = "Pre-1980 eruptive history of Mount St. Helens, Washington",
    year = "2005",
    booktitle = "Fact Sheet",
    url = "https://doi.org/10.3133/fs20053045",
    doi = "10.3133/fs20053045"
}

What triggered the recent and ongoing eruption of Mount St. Helens? Is it new magma or just leftovers from the 1980s? How long will the eruption continue? Will the magma composition change, and will it become more explosive? The U.S. Geological Survey's (USGS) Cascades Volcano Observatory (CVO) hosted a three‐day workshop at which 25 petrologists addressed these fundamental questions. The workshop began with a review of monitoring data by CVO staff and was followed by presentations and discussions of new petrologic data.

@article{pallister2005a,
    author = "Pallister, John S. and Reagan, Mark and Cashman, Kathy",
    title = "A new eruptive cycle at Mount St. Helens?",
    year = "2005",
    journal = "Eos, Transactions American Geophysical Union",
    abstract = "What triggered the recent and ongoing eruption of Mount St. Helens? Is it new magma or just leftovers from the 1980s? How long will the eruption continue? Will the magma composition change, and will it become more explosive? The U.S. Geological Survey's (USGS) Cascades Volcano Observatory (CVO) hosted a three‐day workshop at which 25 petrologists addressed these fundamental questions. The workshop began with a review of monitoring data by CVO staff and was followed by presentations and discussions of new petrologic data.",
    url = "https://doi.org/10.1029/2005eo480006",
    doi = "10.1029/2005eo480006",
    number = "48",
    pages = "499-499",
    volume = "86"
}

Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre‐eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum temperatures of ∼330°C and TIR data acquired concurrently from a Forward Looking Infrared (FLIR) camera showed maximum temperatures ∼675°C, in narrow (∼1‐m) fractures of molten rock on a new resurgent dome. MASTER and FLIR thermal flux calculations indicated a radiative cooling rate of ∼714 J/m 2 /s over the new dome, corresponding to a radiant power of ∼24 MW. MASTER data indicated the new dome was dacitic in composition, and digital elevation data derived from LIDAR acquired concurrently with MASTER showed that the dome growth correlated with the areas of elevated temperatures. Low SO 2 concentrations in the plume combined with sub‐optimal viewing conditions prohibited quantitative measurement of plume SO 2. The results demonstrate that airborne TIR data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes. Given sufficient resources, the airborne instrumentation could be deployed rapidly to a newly‐awakening volcano and provide a means for remote volcano monitoring.

@article{vaughan2005monitoring,
    author = "Vaughan, R. G. and Hook, S. J. and Ramsey, M. S. and Realmuto, V. J. and Schneider, D. J.",
    title = "Monitoring eruptive activity at Mount St. Helens with TIR image data",
    year = "2005",
    journal = "Geophysical Research Letters",
    abstract = "Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre‐eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum temperatures of ∼330°C and TIR data acquired concurrently from a Forward Looking Infrared (FLIR) camera showed maximum temperatures ∼675°C, in narrow (∼1‐m) fractures of molten rock on a new resurgent dome. MASTER and FLIR thermal flux calculations indicated a radiative cooling rate of ∼714 J/m 2 /s over the new dome, corresponding to a radiant power of ∼24 MW. MASTER data indicated the new dome was dacitic in composition, and digital elevation data derived from LIDAR acquired concurrently with MASTER showed that the dome growth correlated with the areas of elevated temperatures. Low SO 2 concentrations in the plume combined with sub‐optimal viewing conditions prohibited quantitative measurement of plume SO 2. The results demonstrate that airborne TIR data can provide information on the temperature of both the surface and plume and the composition of new lava during eruptive episodes. Given sufficient resources, the airborne instrumentation could be deployed rapidly to a newly‐awakening volcano and provide a means for remote volcano monitoring.",
    url = "https://doi.org/10.1029/2005gl024112",
    doi = "10.1029/2005gl024112",
    number = "19",
    volume = "32"
}

@article{lehto2013source,
    author = "Lehto, Heather L. and Roman, Diana C. and Moran, Seth C.",
    title = "Source mechanisms of persistent shallow earthquakes during eruptive and non-eruptive periods between 1981 and 2011 at Mount St. Helens, Washington",
    year = "2013",
    journal = "Journal of Volcanology and Geothermal Research",
    url = "https://doi.org/10.1016/j.jvolgeores.2013.02.005",
    doi = "10.1016/j.jvolgeores.2013.02.005",
    pages = "1-15",
    volume = "256"
}