HR: 13:45h
AN: V43D-01 INVITED     [Abstracts]
TI: Emplacement of Basaltic Lava Flows: the Legacy of GPL Walker
AU: * Cashman, K V
EM: cashman@uoregon.edu
AF: Katharine Cashman, Dept of Geological Sciences University of Oregon, Eugene, OR 97403 United States
AB: Through his early field measurements of lava flow morphology, G.P.L. Walker established a framework for examination of the dynamics of lava flow emplacement that is still in place today. I will examine this legacy as established by three early papers: (1) his 1967 paper, where he defined a relationship between the thickness of recent Etna lava flows and the slope over which they flowed, a relationship that he ascribed to lava viscosity; (2) his 1971 paper, which defined a relationship between lava flux and the formation of simple and compound flow units that he used to infer high effusion rates for the emplacement of some flood basalt lavas; and (3) his often-cited 1973 paper, which related the length of lava flows to their average effusion rate. These three papers, all similar in their basic approach of using field measurements of lava flow morphology to extract fundamental relationships between eruption conditions (magma flux and rheology) and emplacement style (flow length and thickness), firmly established the relationship between flow morphology and emplacement dynamics that has since been widely applied not only to subaerial lava flows, but also to the interpretation of flows in submarine and planetary environments. Important extensions of these concepts have been provided by improved field observation methods, particularly for analysis of flowing lava, by laboratory measurements of lava rheology, by the application of analog experiments to lava flow dynamics, and by steady improvement of numerical techniques to model the flow of lava over complex terrain. The real legacy of G.P.L. Walker's field measurement approach, however, may lie in the future, as new topographic measurement techniques such as LIDAR hold exciting promise for truly quantitative analysis of lava flow morphologies and their relationship to flow dynamics.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8429 Lava rheology and morphology
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005