Magma Mixing in 'Real-Time': A Case Study of the 2006 Eruption of Augustine Volcano, Alaska
Brandon Browne
Department of Geological Sciences
California State University, Fullerton
Wednesday, April 27th, 2011
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Abstract: The frequency and dynamic nature of volcanic eruptions are strongly influenced by a variety of open-system processes that exemplify subvolcanic plumbing systems in island arc volcanoes, including the accumulation, mixing, crystallization, ascent, and eruption of magma at the surface. Investigations designed to uncover the dynamics and timescales of these processes at active and well-monitored volcanoes, where the unique opportunity for integration of petrological datasets with 'real-time' geophysical observations exists, are dramatically advancing our understanding of magma plumbing systems and improving our ability to effectively monitor volcanic activity. The 2006 eruption of Augustine Volcano, located in Cook Inlet Alaska, represents an ideal opportunity to investigate the timescales and dynamics of open-system processes at volcanoes because (1) it is one of the world's most active volcanoes with 6 major explosive eruptions in the past 130 years; (2) it is one of the most well-instrumented volcanoes in the Aleutian Islands in terms of both seismic and geodetic monitoring devices, with 9 real-time seismic stations and 6 real-time continuously recording telemetered GPS stations located within 6 km of the summit; and (3) several investigations focusing on a variety of petrological, experimental, geochemical, geophysical, and sedimentological aspects of the 2006 eruption are being carried out simultaneously, which serve as a valuable chance to collaboratively test hypotheses across different datasets. Findings from this study provide petrological and geochemical constraints that can be used to test recent petrological and geophysical models calling for basaltic magma intruding into the silicic magma reservoir up to 6 months prior to the onset of the eruption (e.g., Cervelli and Coombs, 2006; Larsen et al., 2010). Research discussed in this seminar will include descriptions of the petrologic characteristics of previously unrecognized basalt, which is preserved as quenched basaltic inclusions in 2006 deposits (Steiner, 2009), results from diffusion modeling of concentration gradients in compositionally zoned crystals in inclusions and host andesites, and "fingerprinting" of crystal phases through major and trace element analyses.
Biography: Dr. Browme's education includes a BS in Geology and BS in Environmental Science from Oregon State University followed by a MS and PhD in Geology from the University of Alaska Fairbanks. He's currently an Assistant Professor in the Department of Geological Sciences at California State Fullerton. His research focuses on relating magma chamber processes with volcanic eruption styles so as to advance volcanic assessment and risk reduction efforts at active volcanoes. He has studied volcanic processes for the past 11 years at volcanoes in the USA, Japan, Kamchatka, Mexico and Chile.
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