Investigation of ash disaggregation within volcanic plume conditions

Volcanic eruptions eject ash into the atmosphere, which can be hazardous to air travel, infrastructure, and human health. Most ash particles are small, and they can travel thousands of kilometers away. In many eruptions, ash particles combine into larger clusters, so they fall from the eruption cloud closer to the volcano. Large clusters can also break up (or "disaggregate") into smaller particles, which can alter where the ash falls. Electrical forces, moisture, and flow turbulence are factors that determine the formation or disaggregation of ash clusters. The effect of clustering is critical to make accurate forecasts of volcanic hazards. Most models do not include clustering and no models include disaggregation. This project will use experiments that help scientists examine ash clusters to quantify the fallout of volcanic ash. Results will help produce more accurate predictions of ash fallout for hazard assessments. Hands-on demonstrations of this research will be shared at the Oregon Museum of Science and Industry (OMSI). This project focuses on ash disaggregation, using detailed experiments to develop improved computational models of ash fallout. Our research team will use high-speed visualization of particle impacts, measuring their collision behavior directly. Tests will examine a variety of three-body collisions within a humid chamber, considering conditions relevant to volcanic ash clouds. Particles will range in size, material, and porosity, similar to actual clusters. The measurements will determine the quantitative likelihood of disaggregation. These results will be integrated into a volcanic plume model, providing more accurate predictions of ash fallout for hazard assessment. In addition, the findings will be presented to the public through a series of hands-on demonstrations at the Oregon Museum of Science and Industry (OMSI). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.