Collaborative Research: Linking pyroclastic surge dynamics and deposits through integration of field data, multiphase numerical modeling, and experiments?

Project: Research project

Project Details


Overview: Many volcanoes produce devastating pyroclastic currents at some point during their lifetimes, and nearly all such events include currents that contain low volume concentrations of particles (~0.1-5 volume percent). These dilute currents, referred to as pyroclastic surges, are more mobile than concentrated currents, and as such are capable of surmounting topography; therefore, pyroclastic surges are extremely dangerous to humans and infrastructure. Although much effort has focused on interrogating the deposits of concentrated currents (e.g., ignimbrites), less work has been done on quantitatively linking pyroclastic surge deposits with the dynamic conditions of the currents themselves, despite their more common occurrence. Surge deposits often include a range of facies, including dune- and planar-bedded, along with massive deposits that in some cases record syn-depositional remobilization to form concentrated flows. Much previous work interpreted these facies in terms of familiar bed form regimes from the literature on sediment transport in open channel water flows, but there are several complications to this analogy. Similarly, controls on larger-scale parameters such as proximal-to-distal facies variations, runout, and damage potential are poorly understood.
We will address the following research questions:
At the local scale (e.g., individual outcrop or group of outcrops), what are the relationships of bed forms and facies to sedimentation from suspended load, bed load flux, and local topography?
At the large scale (proximal to distal), what are the roles of sedimentation, topography, initial temperature, mass flux, and atmospheric entrainment on large-scale facies distribution, runout distance, and damage potential?
The proposed work includes three components. (1) Detailed field studies will focus on two well-preserved, young deposits (Ubehebe volcano, California; Crater Elegante, Sonora), with documentation of facies, grainsize, and componentry as functions of distance from vent and local topographic setting. (2) Experiments will test and extend a simple relationship between dune-form parameters measurable in the field, bed load flux, and suspended load sedimentation flux. (3) Multiphase numerical modeling will use adaptive mesh refinement (AMR) to resolve fluxes near the bed, will improve the numerical solution of coupling between gas and very fine ash (key for surge transport and deposition), and will use unstructured mesh technology to model surge transport over complex natural terrains.
Intellectual Merit. Volcanology advances most rapidly when quantitative links can be made between deposits and eruption processes, which in turn allow reconstruction of eruptions and development of hazard assessments. Tephra fallout deposits are the clearest example of this approach, where spatial distribution data on fall deposit thickness (mass per unit area), and clast size and density can be inverted to determine the volume, column height and mass discharge rate of a sustained eruption. This project will make significant progress toward a similar approach based upon surge deposits. The fieldwork will fill in important gaps, and clarify some misunderstandings, in our understanding of surge deposits. Finally, tThe experimental work will be a significant step in inverting quantifiable deposit characteristics with transport and deposition dynamics, and should apply to many natural, rapidly-sedimenting lateral flows. The project will substantially advance multiphase models of volcanic gas-particle flows applicable to any explosive volcanic flow - and the resulting code(s) will be open source and publicly available. The integration of these approaches within the context of a single project will result in major new advances.
Broader Impacts. The project integrates a new team of US-based researchers using multidisciplinary approaches to volcanology, including collaboration between academics and the USGS (for the Ubehebe work); both of these are consistent with recent national-level strategic planning for US volcano science. The project team is diverse and will promote further diversity through involvement of undergraduates and at least one PhD student from traditionally underrepresented groups. The two funded PhD students will receive cross-training at two participating universities that have different foci in the proposed work, providing broad background for the students. In addition to peer-reviewed publications, the project results will be posted as learning modules to for anyone to use, and the work will be publicized to achieve high visibility with the lay public. The field data is relevant for Mars analog studies.
Effective start/end date6/15/215/31/24


  • National Science Foundation (NSF): $274,006.00


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