Collaborative Research: Physical Properties of Bubble- and Crystal-bearing Melts and Their Implications for Eruption Dynamics: Integrated Theoretical, Experimental and Field-based

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COLLABORATIVE RESEARCH: Physical Properties of Bubble- and Crystal-bearing Melts and their Implications for Eruption Dynamics: Integrated Theoretical, Experimental and Field-based studiesEAR-0207362; EAR-0207471PIs: Cashman&Wallace; Manga Magma must ascend to the Earth's surface prior to erupting. Field and theoretical studies over the past decade have shown that the rate of magma ascent plays a critical role in determining the style, and violence, of the ensuing eruption. This dependence results from physical changes that the magma undergoes as it ascends (decompresses). Bubbles nucleate, grow, and coalesce during decompression; crystals may also nucleate and grow. The presence of bubbles and crystals, in turn, affects the magma's ability to flow (its rheology), and thus its continued ascent. For this reason, development of an accurate model of magma ascent and eruption requires that we understand both the distribution of bubbles and crystals as a function of depth below the Earth's surface and the effect of bubbles and crystals on magma rheology. We propose to address both of these questions through a combination of experimental, theoretical and field-based studies. Our specific goals are: (1) to determine the effect of suspended crystals on the rheology of bubble-bearing melt; (2) to use the bubble structure of volcanic samples to estimate shear (velocity) profiles across volcanic conduits; and (3) to examine the permeability (bubble-interconnectedness that permits gas escape) of volcanic clasts as a function of both their bubble and crystal content.