Dawn Ruth
The Geological Sciences Colloquium Series presents Dawn Ruth on “Open Questions on Open Vent Volcanoes: Case Studies of Llaima (Chile) and Mayon (Philippines)” on Nov. 30 at 2 p.m. in Clippinger 205.
Ruth is a Visiting Assistant Professor of Geological Sciences at Ohio University.
Abstract: Open vent volcanoes are defined by prolonged passive degassing, frequently punctuated by moderate, but sometimes violently explosive behaviour. These systems can be found in all tectonic settings and often near areas of high population density. Despite this, studies are generally limited to relatively few, well-studied examples (e.g. Stromboli), though the database is expanding. I will address two fundamental questions concerning open vent systems. The first question is: what causes open vent volcanoes to transition from passive to explosive behaviour? This question will be answered in the context of the 2008 violent Strombolian eruption of Llaima volcano, Chile. I will discuss the magmatic processes associated with the eruption onset using a variety of geochemical and textural tools. The end product is a conceptual model of the plumbing system, and a scenario to explain transitions from passive to explosive behaviour. The second question is: what is the long term nature of open vent plumbing systems, and do they change between eruptive events of similar size? The 20th century eruptions of Mayon volcano are used to answer this question. Using mineral chemistry and diffusion modelling, I will assess how magmatic processes associated with eruption triggering, and the intrinsic parameters of the plumbing system change through time. I will compare the findings of these projects to work in the literature to develop a general conceptual model for open vent volcanoes.
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