9316739 Voight The proposed research focuses on debris flows and is intended as a contribution to the Decade Volcano Program of the International Decade of Natural Disaster Reduction (IDNDR). It has the general objectives to enhance our understanding of past sector-collapses via characterization of deposits and reconstruction of source areas, and to improve our understanding of mechanisms of transformation of debris avalanche to cohesive debris flows. These objectives will be met through detailed study of megaclast and matrix facies relationships in flow deposits, and detailed megaclast mapping of lithologies, igneous structures, key alteration minerals, and textures. A primary task of the proposed research is to characterize the megaclasts and adjacent matrix in the Greenwater Lahar-Osceola Mudflow deposit. The study should significantly contribute to our understanding of cohesive debris flow processes and hazards at Mount Rainier and similar volcanoes worldwide.