Mechanical Controls on Eruptions
- Author(s): Rudolph, Maxwell Lutman
- Advisor(s): Manga, Michael
- et al.
Processes that transport heat and mass govern the long-term evolution of planets and are responsible for surface geological features. This dissertation addresses the thermal and mechanical evolution of icy bodies and the mechanics of geyser and mud volcano eruptions.
Some surface features on Europa have been interpreted as cryovolcanic deposits, but conduits are required in order for water to erupt from a subsurface ocean. Results from a model of fracture penetration indicate that it is unlikely that downward propagating fractures can reach a subsurface ocean on Europa, but that Enceladus' ice shell may be completely cracked. The mechanics of ice shell fracture depend on the stress state in the ice shell, which in turn depends on the thermal history due to coupling between ocean pressure, ice shell thickening, and stresses in the overlying ice shell. Numerical calculations that account for the development of Crystallographic Preferred Orientation (CPO) in ice indicate that CPO-induced viscous anisotropy has first order effects on convective velocity and heat transport, but that the thickness of the stagnant lid precludes remote detection of CPO under conditions relevant to the Galilean Satellites.
Mud volcanoes near the Salton Sea, Southern California responded to the April, 2010 El Mayor-Cucapah earthquake and another smaller event. Analysis of the frequency and amplitude of shaking experienced during events that triggered eruptions as well as several events that did not trigger eruptions reveals that the triggering process is frequency dependent. The Lusi mud eruption in East Java, Indonesia provides an unprecedented opportunity to study a large mud eruption from start to end. An analysis of ground deformation during the first five years of Lusi's eruption indicates that progressive mobilization of mud occurred, supporting a new conceptual model for mud volcanism that is in some ways analogous to large caldera-forming silicic volcanic eruptions. Like mud volcanoes, geysers provide an opportunity to study an erupting system analogous to volcanoes. Ground deformation at Calistoga Geyser is cyclic and reflects the filling and draining of the geyser's plumbing system.