Date of Award

2009

Degree Type

Dissertation

First Advisor

Steven N. Carey

Abstract

The primary objective of this work was to characterize the main eruptive and atmospheric conditions responsible for the formation of widespread tephra deposits observed within the geologic record. To accomplish these objectives, the Lagrangian ash dispersal model Puff was initially used to simulate two historic eruptions, the 1980 eruption of Mt. St. Helens (MSH) and the 1991 eruption of Mt. Pinatubo. Two high-resolution atmospheric reanalysis datasets (ERA-40 and NCEP/NCAR-40) were used for the simulations allowing trajectory analysis up to altitudes of 50 km. Results from these Puff simulations were directly compared to visible, infrared, and ultraviolet satellite images taken during the eruption. Puff was then used to simulate the Youngest Toba Tuff eruption (YTT, 74 ka) using monthly averaged modern reanalysis winds. Finally, Puff was used to evaluate the eruptive and atmospheric conditions near Central America responsible for depositing the numerous tephra layers within the western Caribbean basin recovered during Ocean Drilling Project (ODP) Leg 165.

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