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February 7 @ 4:00 pm - 5:00 pm CST

EEPS Seminar:  Thomas Jones, University of Durham, UK


Title:     Magma Dynamics in Basaltic Conduits

 Abstract:   Basaltic volcanoes are responsible for the bulk of the planet’s magma output. Their eruptions are often spectacular and can have serious impacts on a local scale (through lava flows) and regional scale (through emission of ash and toxic gases). However, hazard planning and mitigation is challenging because these eruptions can be highly variable both temporally, lasting from hours to months, and spatially, localizing from a long, linear fissure to a discrete vent.  In this talk, I will explore the role that magma dynamics play in controlling the evolution of basaltic fissure eruptions in time and space. Firstly, I will present results from a detailed field investigation of the proximal deposits from the 1969 fissure eruption of Mauna Ulu, Kīlauea, Hawai‘i. Exceptional preservation of the deposits allows us to reconstruct vent-proximal lava drainage patterns and to assess the role that drainage played in controlling vent localization. Secondly, through a series of scaled analogue experiments, I will explore how the simultaneous drainage of dense, degassed, viscous magma and upwelling of less dense, less viscous magma can influence flow processes in the volcanic conduit. This convective system is characterized via the dimensionless Grashof number (Gr), which is a ratio of viscous to buoyancy forces. At low Gr, efficient laminar flow is observed with narrow, well-defined fingers of upwelling fluid separated by broad regions of downwelling fluid. As Gr increases, the flow becomes increasingly chaotic and exchange becomes inefficient – no stable fingers or regions of coherent flow are established. Together, these field and lab data suggest that “top-down” lava drainage processes and “bottom-up” convective processes in basaltic fissure eruptions conspire together to control their localization and longevity. This new knowledge advances our understanding of how magma dynamics can influence key, hazard-relevant eruption parameters, such as: mass eruption rate, dynamics of proximal lava flow emplacement, lava fountain vigour, and eruption evolution. This work highlights the importance of understanding the central role of fluid dynamics in shaping volcanic eruptions in order to develop more robust conceptual and physical models of eruptive behaviour – a key component of my fellowship proposal at Rice University


February 7
4:00 pm - 5:00 pm


131 Anderson Biological Laboratory
Rice University, 6100 Main Street
Houston, TX 77005 United States
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