• Thesis and Dissertation Defenses

June 1, 2026 1:00 PM
PAIS 2540

Presenter:

Grant Block

Volcanoes are both creative and destructive forces that have shaped and continue to shape our world from early geologic time to the present day. Continued study of volcanic processes not only better prepares us for monitoring volcanic hazards but also allows us to better understand processes fundamental to Earth as we know it, such as the generation of the atmosphere and accretion of the continents. This defense focuses on an integral part of volcanic processes: the trans-crustal magmatic transport system. Specifically, we investigate regions of these transport systems where magma pools in melt-rich lenses within broader regions of low melt-fraction, mush zones. The thermal, chemical, and rheologic structure of these regions, especially in the mid to upper crust, strongly controls the style and frequency of volcanic eruptions. We probe these systems by constructing three-dimensional finite element models (using the open-source code PyLith) focusing on surface deformation generated by pressurizing tabular bodies within a heterogeneous, viscoelastically deforming crustal compliant region. These models enable us to use geodetic measurements (such as InSAR and GNSS) of volcano deformation to constrain properties of magma/mush systems such as: pressurization rates; geometry and depth of melt-rich regions into which fluid is likely being injected or extracted; the geometry of broad, melt-poor mushy, or otherwise compliant regions; and the rheology of these compliant regions. We apply our models to two magmatic systems with vastly different surface deformation histories: the Socorro Magma Body and Yellowstone. By using seismic tomography to constrain the geometry of the compliant region in both cases, as well as magnetotelluric tomography in Yellowstone, we are able to produce reasonable fits to their observed surface deformations. Our work constrains the local crustal rheology and reservoir pressurization history for each system. The defense concludes with a new software development effort within the open-source PyLith code to enhance future models of magma/mush interaction using a poro-viscoelastic rheology.   This allows for the coupling of porous-flow with solid-state viscous relaxation, both key processes that control the deformation of crustal compliant regions within magmatic transport systems.