SCEC Award Number 15140 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Beyond Elasticity: Deformation Models Incorporating Off-fault Plasticity
Investigator(s)
Name Organization
Kaj Johnson Indiana University
Other Participants
SCEC Priorities 1a, 1b, 4b SCEC Groups WGCEP, Geodesy, SDOT
Report Due Date 03/15/2016 Date Report Submitted 11/14/2018
Project Abstract
 An important problem for the Southern California Earthquake Center (SCEC) is to resolve the issue of how much present-day deformation across southern California occurs as slip on known faults and how much deformation is distributed through the crust. One of the surprising results of the UCERF3 kinematic deformation models is that all the models required 20-30% of the total deformation across California to occur as distributed, off-fault strain. In 2015 I was funded by SCEC to develop numerical models of crustal deformation that incorporate off-fault plasticity. For this work, my post-doc and student and I have developed elasto-plastic finite element models of long-term (steady-state) deformation in southern California in which off-fault plasticity is modeled with Drucker-Prager yielding. We have some preliminary results with a simplified Southern California fault model. We have compared elastic models with elasto-plastic models and find that the introduction of off-fault plasticity dramatically alters the distribution of computed fault slip rates.
Intellectual Merit This work contributes directly to the "Beyond Elasticity" theme of SCEC. An important problem for the Southern California Earthquake Center (SCEC) is to resolve the issue of how much present-day deformation across southern California occurs as slip on known faults and how much deformation is distributed through the crust. This work addresses this issue directly through numerical simulations.
Broader Impacts This work help fund the research of a graduate student at Indiana University and also motivated research for my post-doc and a new graduate student.
Exemplary Figure Figure 2. Results of “thin sheet” model illustrated in Figure 1. (a) maximum shear strain rates for elastic model and elasto-plastic model after 10K years. (b) instantaneous velocities for elastic model and elasto-plastic model after 10K years.