Exciting news! We're transitioning to the Statewide California Earthquake Center. Our new website is under construction, but we'll continue using this website for SCEC business in the meantime. We're also archiving the Southern Center site to preserve its rich history. A new and improved platform is coming soon!

Off-fault deformations and shallow slip deficit from dynamic rupture simulations with fault zone plasticity

Daniel Roten, Kim B. Olsen, & Steven M. Day

Published August 11, 2017, SCEC Contribution #7300

Kinematic source inversions of major (M ≥ 7) strike-slip earthquakes show that the slip at depth exceeds surface displacements measured in the field, and it has been suggested that this shallow slip deficit (SSD) is caused by distributed plastic deformation near the surface. We perform dynamic rupture simulations of M 7.2–7.4 earthquakes in elastoplastic media and analyze the sensitivity of SSD and off-fault deformation (OFD) to rock quality parameters. While linear simulations clearly underpredict observed SSD and OFDs, nonlinear simulations for a moderately fractured fault damage zone predict a SSD of 44–53% and OFDs of 39–48%, consistent with the 30–60% SSD and 46±10% (1σ) OFD reported for the 1992 M 7.3 Landers earthquake. Both SSD and OFDs are sensitive to the quality of the fractured rock mass inside the fault damage zone, and surface rupture is almost entirely suppressed in poor quality material.

Citation
Roten, D., Olsen, K. B., & Day, S. M. (2017). Off-fault deformations and shallow slip deficit from dynamic rupture simulations with fault zone plasticity. Geophysical Research Letters, 40, 1-10. doi: 10.1002/2017GL074323.