The near and far of pore pressure during landslide and earthquake ruptures.

摘要

Geological materials near the Earth's surface and within the Earth's crust contain pore spaces, largely saturated with water. In this work I study how changes in the pressure of this saturating pore fluid affect deformation, focusing on the deformation of shear ruptures occurring during an earthquake or a landslide. I represent ruptures in both contexts as sliding fractures to better understand the conditions under which they propagate. Elevated pore pressures are frequently cited as a nucleating mechanism, particularly in the landslide context. For undersea landslides, these elevations build upon a preexisting pressurization founded by gradual sedimentation and consolidation, studied here in a simple framework. During initiation, the slow growth of the fracture may give way to fast propagation, corresponding to the source of earthquake shaking and the origin of landslide acceleration. I quantify the extent to which pore pressures, geometry, and material response determine the development. During the fast phase of rupture propagation, pore pressure changes may serve to inhibit or enable inelastic deformation of material away from the slip surface. Such deformation is one of the signatures left by an earthquake. I implement a convenient method for accounting for saturation during rapid rupture propagation and evaluate the impact on the distribution and magnitude of the inelastic deformation. Returning to the slip surface, this inelastic deformation affects fluid flow there on the short timescales of dynamic rupture. I enhance an existing poroelastic model to include these effects.