IGPP is pleased to invite you to join its Fall 2022 Seminar Series presentation featuring ETH Zurich's Luca Dal Zilio. Dr. Dal Zilio's talk, "Fault instabilities in multiphase flow through porous media?" will be available via Zoom on THURSDAY, November 3, 2022, starting at 12:00pm. Zoom: https://ucsd.zoom.us/j/93891695935pwd=TVpFYTFLVW9zbUZzOGpEajFhcmFmUT0 Password: igpptalk
Time: 12:00 pm, Pacific Time
Location: Revelle 4000 (on-site with a zoom link)
Abstract: Flow and transport through porous media is ubiquitous in nature. They are key processes behind subsurface resources, including oil and gas, geothermal energy, and groundwater. They also mediate geohazards such as landslides, volcanic eruptions and earthquakes. Central to many of these processes is the strong coupling between deformation processes, phase transitions, and porous media flows on geologic faults. Multiphase flow with phase transitions often leads to dynamic systems that are far from thermodynamic equilibrium.
In this talk, I will describe two examples of a two-phase (solid-fluid) system on geologic faults, and new continuum mathematical descriptions to model them. First, I will discuss the role of pore-fluid pressure cycling in controlling the occurrence of slow-slip events and earthquakes over earthquake cycle timescales. Then I propose a new fault model in which stable, rate-strengthening frictional behavior is combined with dynamic weakening due to rapid poroelastic effects, allowing unstable (seismic) slip to occur on nominally stable faults during fluid-injection experiments. Motivated by field and laboratory observations, I will describe how the spontaneous poroelastic compaction and self-pressurization of pore fluid can overcome the initial phase of shear-induced dilatancy, thus allowing the propagation of dynamic rupture in the form of pulse-like pore-pressure waves. I will further show that this solid-modulated fluid percolation mechanism is crucial to our understanding of fault slip, from creep and slow-slip events to fast dynamic rupture. Finally, I will discuss how this research on fluid-solid coupling in porous media can stimulate new questions at the interface of geosciences, engineering, and material sciences.