The primary mission of the Fault and Rupture Mechanics focus group in SCEC3 is to develop physics-based models of the nucleation, propagation, and arrest of dynamic earthquake rupture. We specifically solicit proposals that address this mission through field, laboratory, and modeling efforts directed at characterizing and understanding the influence of material properties, geometric irregularities, and heterogeneities in stress and strain over multiple length and time scales (A7-A10, B1, B4), and that will contribute to our understanding of earthquakes in the Southern California fault system.

Proposed studies should aim to:

• Determine the properties of fault cores and damage zones and their variability with depth and along strike, including the width and particle composition of actively shearing zones, extent, origin and significance, of on- and off-fault damage, and poroelastic properties (A7-A11)
• Determine the relative contribution of on- and off-fault damage to the total earthquake energy budget, and the absolute levels of local and average stress (A7-A10)
• Investigate the relative importance of different dynamic weakening and fault healing mechanisms, and the slip and/or time scales over which these mechanisms operate (A7-A10)
• Characterize the probability and possible signatures of preferred earthquake rupture direction (A7-A10, B1, B4)
• Develop realistic descriptions of heterogeneity in fault geometry, properties, stresses, and strains, and tractable ways to incorporate heterogeneity in numerical models (A10-11, B1, B4)
• Understand the influence of small-scale processes on larger-scale fault dynamics (A7-11, B1, B4)
• Evaluate the relative importance of fault structure, material properties, and prior seismic and aseismic slip to earthquake dynamics, in particular, to rupture initiation, propagation, and arrest, and the resulting ground motions (A7-A10, B1)