Collaborative Research: Transport of magma in the near surface at small volcanoes- Experimental intrusion of basaltic melt into unconsolidated sediments

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This project deals with the interaction of magma and the materials through which it rises to feed small-volume volcanoes (the most abundant volcanic landforms on Earth). When magmatic interaction involves loose sediments that contain variable amounts of water or ice, the magma may behave in a variety of ways - passing through the material, causing explosions or even stopping before reaching the surface. These different behaviors influence how a volcano will erupt, and this project will enhance the ability to anticipate the behavior of future eruptions, which is vital for saving lives and protecting infrastructure. This project involves experiments that will inject 30 liters (8 gallons) of basaltic melt into different types of loose sediment - dry, wet, and frozen. The experiments provide the opportunity to characterize the conditions of magma and sediment interactions that result in these diverse behaviors. Characterization of conditions, which are limited by physical experiments will be expanded using computer simulations and comparison with natural products from an eroded volcanic field (71 Gulch, Idaho, USA). These experiments are the first of their kind and provide valuable constraints on the flow of magma into sediments and will help better interpret natural deposits of past volcanic eruptions and provide inputs for models of future activity. This project will involve the training of undergraduate and graduate students with results and facilities shared with the scientific community. At the same time, the novel nature of the experiments will provide ample opportunities to engage public interest in science and volcanoes through videos and public facing blogs. The behavior of magma in the near surface directly influences the potential for eruptions and their resulting eruptive styles. To reach the surface, magma commonly must travel through unconsolidated sediments. This interaction influences the transport of magma, the stability of volcanic piles, and the potential for phreatomagmatic explosions. Meter-scale experiments of basaltic melt-sediment interactions will be integrated with computational simulations and field work to bridge the scale from experimental results and small natural deposits to a wider range of natural scenarios. The scale of the proposed experiments (mm to m) is large enough to overlap with natural systems (mm to 10’s of m). The experimental products, created using an automated plunger-driven magma extrusion device, will be both modeled numerically and compared with similar-sized natural magma-sediment deposits at the 71 Gulch Volcano, Idaho, USA. This field area contains deposits at both the experimental scale and larger, making it an ideal natural laboratory to investigate the scaling behavior of magma sediment interactions. The experimental and numerical results will be used to determine how long magma is available for mechanical mixing and thermal interactions, contributing to an understanding of how eruptions progress, and what conditions are necessary for explosive magma-sediment interactions. Specifically, the project will test two hypotheses: 1) The flow rate and temperature of the intruding magma is more important than the sedimentary host conditions in determining whether basaltic magma will pass through, mingle with, or be arrested by an unconsolidated sedimentary host at near surface conditions. 2) The textures and geometries of natural deposits of mingled basaltic magma and unconsolidated sediments can be used to estimate the flux rate and time scale at the time of formation. Experimental and numerical results will enable detailed quantitative interpretations of the forces and thermal history recorded in natural deposits in ways not previously possible.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.