9316656 Bursik The primary hypothesis to be tested is that the manner in which elutriated ash clouds (of which 'coignimbrite' ash clouds are a subset) are generated is strongly dependent upon the interaction of pyroclastic flows and surges with the topography surrounding a volcano. Our objectives are therefore to understand ash cloud generating mechanisms and flow and surge mechanisms especially as they are affected by topography. The proposed research will consist of detailed sedimentological measurements, laboratory experiments and theoretical modeling. Field work will consist of a novel sampling strategy applied to the 1982 deposits of El Chichon volcano, Mexico, at closely spaced sites lying along traverse that traverse that parrallel flow directions. The sampling strategy will yield quantitative data that can be used to test theoretical models of flow behavior. Laboratory experiments will be conducted in conjunction with the analysis of the field data and the development of theoretical models to provide constraints on interpretations of field data and validation theory. The proposed activity will yield increased understanding of the mechanisms through which ash clouds are elutriated from pyroclastic flows and surges.
