A multi-sensor approach to determining volcanic plume heights in the North Pacific
AuthorEkstrand, Angela L.
North Pacific Region
Redoubt Volcano (Alaska)
Augustine Volcano (Alaska)
Okmok, Mount (Alaska)
Cleveland, Mount (Volcano : Alaska)
Kasatochi Volcano (Alaska)
Sarychev Volcano (Russia)
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AbstractDuring a volcanic eruption, accurate height information is necessary to forecast a volcanic plume's trajectory with volcanic ash transport and dispersion (VATD) models. Recent events in the North Pacific (NOPAC) displayed significant discrepancies between different methods of plume height determination. This thesis describes two studies that attempted to resolve this discrepancy, and identify the most accurate method for plume height determination. The first study considered the 2009 eruption of Redoubt Volcano. This study found that the basic satellite temperature method, in which satellite thermal infrared temperatures are compared to temperature-altitude profiles, vastly underestimates volcanic plume height due to decreased optical depth of plumes soon after eruption. This study also found that the Multi-angle Imaging SpectroRadiometer (MISR) produced very accurate plume heights, even for optically thin plumes. The second study investigated the application of MISR data to multiple eruptions in the NOPAC: Augustine Volcano in 2006, Okmok, Cleveland, and Kasatochi volcanoes in 2008, and Redoubt and Sarychev Peak volcanoes in 2009. This study found that MISR data analysis retrieves accurate plume heights regardless of grain size, altitude, or water content. Exceptions include plumes of low optical depth over bright backgrounds. MISR is also capable of identifying ash clouds by aerosol type.
DescriptionThesis (M.S.) University of Alaska Fairbanks, 2012
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Volcano Seismology From Around The World: Case Studies From Mount Pinatubo (Philippines) Galeras (Colombia), Mount Wrangell And Mount Veniaminof (Alaska)Sanchez-Aguilar, John Jairo; McNutt, Stephen R.; Power, John A.; Freymueller, Jeffrey T.; Christensen, Douglas; Eichelberger, John (2005)A compilation of research papers in volcano seismology is presented: (1) to study the configuration of magma systems beneath volcanoes, (2) to describe unexpected effects of the shaking from a regional earthquake on volcanic systems, and (3) to integrate seismicity investigations into a conceptual model for the magma system of a volcano. This work was undertaken because much research in volcano seismology is needed to help in hazard assessment. The possible configuration of magma systems beneath Mount Pinatubo, Philippines, and Galeras Volcano, Colombia, is studied with b-value mapping. We suggest models for earthquake-volcanoes interactions by studying the declines in local seismicity at Mt. Wrangell and Mt. Veniaminof, Alaska, following the 3 November 2002 Denali Fault Earthquake (DFE). Finally, a model for the magmatic-hydrothermal system beneath Mt. Veniaminof is proposed by deriving a velocity model and relocating the earthquakes, and by studying the temporal changes of frequencies and attenuation (Q) at the source of long-period (LP) events. Results from b-value mapping confirm that volcanoes are characterized by localized zones of high b-values, and also indicate that the internal structure of volcanoes is variable. Analyses of the background seismicity at Mt. Veniaminof suggest that earthquakes result from locally-induced stresses and that LP events may represent the response of a shallow hydrothermal system to heat input from below. The study of declines in seismicity at Mt. Wrangell and Mt. Veniaminof volcanoes following the DFE indicates that the dynamic shaking from regional shocks can physically damage a volcano and together with the static stress changes can affect the local seismicity for extended periods. We conclude that the use of simple methods allows a better understanding of the seismicity at volcanoes in Alaska, but most importantly in developing countries where the small number of seismograph stations puts challenging limitations for research.