Influence of Plastic Deformation on Bimaterial Fault Rupture Directivity
Nora DeDontney, Elizabeth L. Templeton, James R. Rice, & Renata DmowskaPublished 2011, SCEC Contribution #1488
Material juxtapositions across mature faults are a common occurrence. Previous work has found that this elastic mismatch results in a rupture that will preferentially propagate in the direction of slip displacement on the more compliant side of the fault, with more off-fault damage in the stiffer material. This result has implications for inferring preferred rupture directions based on observations of damage zone asymmetry. We perform a complete numerical investigation of the role of the stress state on the distribution of plastic deformation and the direction of preferred rupture propagation. We show that there are important factors, in addition to the elastic mismatch, which control the preferred direction of propagation as well as the side of the fault in which dam- age predominately accumulates. The orientation of the most compressive stress is the controlling factor in where the plastic deformation occurs. For different orientations, plastic deformation can accumulate in either the stiffer or the more compliant material. For high angles of most compressive stress, the aforementioned preferred rupture direction prediction holds true, but the off-fault plastic response can reverse that direction for low angles of most compressive stress so that the rupture will preferentially propagate in the direction of slip displacement in the stiffer material.
Citation
DeDontney, N., Templeton, E. L., Rice, J. R., & Dmowska, R. (2011). Influence of Plastic Deformation on Bimaterial Fault Rupture Directivity. Journal of Geophysical Research: Solid Earth, 116, B10312. doi: 10.1029/2011JB008417.
