Rheology for near real time forecasting of lava flows

Effective civil protection during effusive volcanic eruptions relies on accurate assessment of three main questions: 1. Where is the eruptive vent? 2. What areas will the lava flows affect? and 3. How fast will lava reach certain areas? Forecasting methods for lava flow paths and velocities require a detailed understanding of the lava’s flow properties (i.e. how viscous it is), the slope of the ground that the lava is flowing on and how much lava is erupted over a certain time interval. As lava flows down a volcano, it cools, crystallizes, and forms and/or loses bubbles, all of which affect how fast and how far lava may flow. An incomplete understanding of how the lava’s flow properties change makes accurate lava flow forecasting, and with that, hazard mitigation ahead of effusive eruptions, civil protection, and management of ongoing eruptive events, difficult. This project is motivated by 1) an incomplete understanding of lava flow properties, 2) a lack of integration of accurate flow properties in lava flow models and 3) the need for shorter response times between eruption onset and availability of lava flow-path forecasts. The project will tackle these challenges using the two most hazardous effusive volcanoes in the world, Nyiragongo and Nyamulagira as type localities. As an example, the 2021 eruption of Nyiragongo claimed over 30 lives, left > 20,000 homeless, destroyed > 3,500 houses, 12 schools, and 3 hospitals – a powerful expression of the impact lava flows can have on human lives. The core objectives are to 1) reconstruct the lava’s flow properties from natural samples 2) measure the lava’s viscosity at conditions relevant to its emplacement, and 3) integrate these data into a framework of satellite informed lava forecasting models. This may enable the development of a satellite-data-driven near-real time protocol for rapid and accurate forecasting of lava flow paths, which can then be applied during effusive eruptions to help guide decision making in civil protection efforts. Project results will also be incorporated into the SUNY Buffalo EarthEd program, providing content for K12 educators serving underrepresented communities, promoting science literacy. The project will support a graduate student at SUNY Buffalo and involves international collaborations (USA, Italy, France, DR Congo) in academia, development aid, and at volcano observatories. Lava rheology varies as a function of temperature, melt composition, crystal, and bubble content as well as strain rate. From eruption to flow cessation, basaltic lavas traverse a range of up to 10 orders of magnitude in their effective viscosity. The resulting non-linear changes in the lava’s transport behaviour determine how it accommodates deformation during emplacement and how fast and how far a lava can flow. The core objectives are to 1) reconstruct the lava’s rheology from natural samples 2) map the lava’s rheology over conditions relevant to their emplacement, and 3) integrate these data into a framework of satellite informed lava emplacement models. Using careful experimental characterization of the lava enables adaptation of a satellite-data-driven near-real time protocol to develop a tool for rapid and accurate forecasting of lava flow emplacement paths. The project will integrate field measurements, textural analysis, and targeted high temperature rheology experiments to generate the first complete rheological flow law for a basaltic lava that is derived from measurements at conditions relevant to lava emplacement and validated with field constraints. Using this flow law, the project will optimize a lava flow emplacement model, and integrate it into an existing near real time satellite monitoring system. This will create a highly adaptable tool for predicting lava flow paths and advance rates that is rooted in and optimized for the core physical property – lava rheology. The project sets out to: 1) Perform detailed petrographic analyses of natural samples and collect and evaluate field data of lava flow geometries 2) Use these in concert with viscosity measurements in controlled atmospheres to reconstruct the lava’s rheology during emplacement. This includes generating critical new data at reduced conditions, which are extremely scarce. 3) Employ the derived data to initialize and calibrate a deterministic lava flow model. This tool may enable near real time lava emplacement forecasting during future eruptions as well as forensic investigations of previous eruptions. The selected type localities enable testing both cooling- and volume-limited lava emplacement scenarios. 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.