Volatile emissions from Cascades cinder cone eruptions have been well-documented; however the implications for understanding the effects that volcanic gases have on surrounding communities have not been addressed. This study examines the hazards from volatile degassing during explosive activity by (1) analyzing S, Cl, and F concentrations dissolved in olivine-hosted melt inclusions and matrix glass from cinder cones located in central Oregon and northern California, (2) estimating the mass of volcanic gas degassed during these eruptions, and (3) predicting gas concentrations downwind of the vent. Analyses reveal that the magmas degassed >88% S, <49% Cl, and <50% F during eruption, equating to a release of ≤4.5 Mt SO2, ≤0.2 Mt HCl, and ≤0.2 Mt HF. Predictions of gas concentrations downwind of the vent provides reassurance that the levels of volcanic gases were not high enough at the time of eruption to present acute or severe health hazards to nearby residents.

Landscapes evolve through a number of processes in response to a wide range of forcing mechanisms. Many of the processes that drive landscape evolution occur at the interface between fluid and sediment. Sediment transport leads to changes in topography that, in turn, influence fluid flow. Feedback mechanisms between topography and fluid flow can lead to the formation of patterns, such as sand ripples, dune fields, parallel channel networks, and periodically spaced valleys. In many cases, the development and evolution of patterns within landscapes are heavily influenced by environmental conditions. Therefore, given relationships between landform features and the underlying processes, present-day landscapes have the potential to be used to infer a record of climatic conditions over the course of their development. An inability to make direct observations over geologically relevant timescales makes it difficult to study the processes that influence landscape evolution. Mathematical models provide a means of quantitatively linking natural patterns and landscape features with physical processes. Patterns in landscapes also provide a simple means of testing quantitative representations of geomorphic processes. In this work, we develop landscape evolution models to study the development of debris-flow-dominated hillslopes, rill networks, and cinder cones. Through a combination of theoretical modeling, analysis of experimental data, and remote sensing data, we attempt to better understand each of these three systems. While each system is interesting in isolation, these and similar studies add to our knowledge of the mathematical representations of processes that are used more generally within the study of landscape evolution.

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