GPR-derived facies architectures: a new perspective on mapping pyroclastic flow deposits
Published:January 01, 2009
N. J. Cassidy, E. S. Calder, A. Pavez, L. Wooller, 2009. "GPR-derived facies architectures: a new perspective on mapping pyroclastic flow deposits", Studies in Volcanology: The Legacy of George Walker, T. Thordarson, S. Self, G. Larsen, S. K. Rowland, Á. Höskuldsson
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Ground-penetrating radar (GPR) is used to image the sub-surface architecture of the 1993 pumice flow deposits at Lascar volcano, northeastern Chile. This non-invasive geophysical technique allowed the determination of the three-dimensional, stratigraphic and facies variations of a deposit that is morphologically pristine but problematic to view internally. The geometry, sedimentological characteristics and compositional nature of the deposit make it ideal for investigation by GPR, which has been successfully used to map deposit-scale variations as well as detailed outcrop-scale features. This work both compliments and extends the interpretation of flow emplacement dynamics postulated for these flows by previous studies. Deposit shape, erosional and non-erosional contacts, buried units and stacked lobes are all informative deposit characteristics that can be readily ascertained from sub-surface imaging. Without such techniques, we are commonly unable to visualize these important features. In a broader context, we present this work in an attempt to demonstrate the suitability of GPR as a tool for studying the emplacement dynamics of pyroclastic currents and to encourage the diversification of applied field techniques in volcanology.
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Studies in Volcanology: The Legacy of George Walker
Professor George Patrick Leonard Walker was one of the fathers of modern quantitative volcanology and arguably the foremost volcanologist of the twentieth century. In his long career, George studied a wide spectrum of volcanological problems and in doing so influenced almost every branch of the field. This volume, which honours his memory and his contributions to the field of volcanology, contains a collection of papers inspired by, and building upon, many of the ideas previously developed by George. Many of the contributors either directly studied under and worked with George, or were profoundly influenced by his ideas. The topics broadly fall under the three themes of lava flows and effusion, explosive volcanism, and volcanoes and their infrastructure.