Endogenic pyroclastic flows may emerge without warning from distal portions of advancing, relatively dry silicic lava, suggesting concentration of volatiles. This project will be an investigation of processes by which volatiles migrate, and will involve the following activities: 1) Modeling of the cooling of a silicic lava flow to quantify processes of crystallization, brecciation and vesiculation; 2) measuring distribution and isotopic signatures of volatiles, and mapping vesicular textures in active dacite domes at St. Helens, Santiaguito, and St. Augustine; 3) characterizing the morphology and energetics of microcracis in silicic lavas through SEM and deformation experiments to evaluate the possible role in volatile transport. The PI will be engaged in field collecting, mapping on Novarupta dome, experimental studies, and synthesis of results.
