Dome collapses are very hazardous. By constraining the conditions under which they occur, those hazards can be anticipated and mapped. The infiltration of water into, and the presence of an active hydrothermal system in a lava dome may contribute significantly to its destabilization. Dome collapses triggered by rainfall have been investigated at the Soufrière Hills volcano on Montserrat, but have not been well considered at other lava dome-producing stratovolcanoes. Several recent studies have combined geological and computational analyses to produce hazard assessments at stratovolcanoes, although the analyses have focused mainly on the results of a dome collapse. There has been limited work to date on modeling the conditions on the interior of domes prior to collapse – particularly the state of the hydrologic system, which can significantly impact the stability of a lava dome.
My work combines multiple physical and computational investigations into lava dome stability, with particular attention to the interaction between water and dome rock. It includes a new application of a multiphase heat and mass transfer code to model the behavior of water in a dome interior, as well as ground-based and remote sensing mapping of structures and zones of hydrothermal alteration on existing domes. The data from these investigations will be combined to provide detailed operating parameters for computational models of dome collapse.
One particular field location, the Santiaguito lava dome complex in Guatemala, is well-suited to an investigation of the effects of water on lava dome stability. The Santiaguito complex, which has been growing for more than 80 years, is exposed to the effects of a tropical climate, which include periods of intense rainfall (from seasonal weather as well as isolated events such as hurricanes). To date, however, it has experienced only a few volumetrically minor dome collapses. There is significant potential for a major dome collapse at Santiaguito, and dome stability investigations there would be invaluable for improving current hazard assessments.
My undergraduate honors thesis at the College of William & Mary focused on the volcanic ash flow tuffs of the Fish Lake Plateau, in the High Plateaus of south-central Utah. My research concerned the Osiris trachyte, a tuff formed by the caldera-forming eruption of Monroe Peak in the Marysvale Volcanic Field (located to the west of the High Plateaus). The Osiris is a highly-welded trachytic ash flow tuff, and contains abundant phenocrysts (especially distinctive, large biotites), as well as several interlayered ash fall deposits and a basal vitrophyre. The Osiris has long been used as a regional marker unit in the Marysvale, and my work continued the mapping and geochemical/petrological characterizations of several authors on the High Plateaus. I also conducted 40Ar/39Ar geochronology with sanidines extracted from samples of the Osiris.