VISCOSITY PATHS: Assessing the Effect of Realistic Cooling Rates on the Evolution of Lava Flow Rheology

North Carolina State University, Raleigh NC

Investigators

Abstract

Lava flows are by far the most common form of volcanic activity. With more than 1 billion people worldwide living near an active volcano, it is imperative to accurately forecast lava flow hazard. While lava flows rarely kill people, they routinely destroy houses and infrastructure, sometimes causing millions of dollars of damage in a single event. In order to mitigate this hazard, this project seeks to understand how lava flows advance. The advance of lava flows largely depends on how they transition from being mainly liquid at eruption to fully solid as they flow away from the vent and cool down. This project will reproduce realistic lava flow cooling paths through laboratory experiments, and measure how lava ability to deform and move changes throughout the process. Further, the team will develop a learning unit on lava flow motion specifically tailored to the unique needs of the ever-growing homeschooling community, thus advancing NSF’s goal of promoting access to STEM learning and training for all citizens. Each quantum of lava within a flow is subject to a unique cooling history, which results in varying crystal assemblages and textures, and ultimately rheology, for any given lava flow in both space and time. State-of-the-art rheological experiments assume either isothermal conditions or constant cooling rates. However, natural lava flows experience much more nuanced cooling histories. The overarching goal of this proposal is to experimentally determine how the crystallization and thus rheology of basaltic lava evolve when subjected to realistic cooling curves. The product will be a detailed, physics-based rheological evolution map of a channelized basaltic lava flow. Because of the key role played by rheology in controlling lava flow advance speed and dynamics, this deliverable will provide the community with a key tool to improve our ability to forecast lava flow emplacement, and to potentially mitigate damage to infrastructure. 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.