Volcanic eruptions are spectacular phenomena, but pose hazards to many populations around the world. Explosive eruptions can eject pyroclastic rocks that radically and quickly alter the landscape, destroy buildings and affect air travel thousands of kilometers away. My research focuses on understanding volcanoes from storage, through decompression (and fragmentation), to eruption. To study those processes I use experimental petrology, laboratory analyses, field work, and experimental volcanology. I work as a curator and geologist in the Department of Mineral Sciences within the Smithsonian Institution's National Museum of Natural History. In addition, I work with the Smithsonian's Global Volcanism Program.
Understanding explosive eruption processes is required for interpreting ancient eruptions and predicting behavior of future eruptions. Observing many eruptions as they occur, however, is dangerous. Further, the size and intensity of eruption plumes and pyroclastic density currents preclude observation into the interiors of those turbulent, hot, particle-laden flows. I use scaled laboratory experiments to what processes control the transport, deposition, and liftoff of pyroclastic density currents.
Eruptions that form lava domes are extremely common. Although the majority of the mass erupts as lava, domes often also eject ash; lava domes thus ride the line between effusive (lava) and explosive (ash and pumice) activity. I use time-lapse photogrammetry to study the Santiaguito lava dome complex at the base of Santa Maria volcano (Guatemala).
Deposits provide important insights into ancient eruptions and eruption processes. Because the largest explosive eruptions occur with global recurrence intervals of tens of thousands of years, and even small caldera-forming eruptions occur on the order of 30-50 years (fortunately), pyroclastic deposits provide our only window into the dynamics of “large” eruptions and the manner in which material is dispersed (e.g. by buoyant plume of pyroclastic density current).
The textures and compositions of volcanic rocks, and the phenocrysts, microlites, and vesicles they contain, provide an important record of volcanic processes that occur prior to and during eruption. Such data provide an important constraint on the temperature and storage pressure of modern volcanic systems, and they provide our only record for older eruptions (e.g. any eruption not monitored using geophysical techniques).