SCEC Award Number 15119 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Development of a broadband 3D pseudo-dynamic rupture generator for geometrically complex faults
Investigator(s)
Name Organization
Kim Olsen San Diego State University
Other Participants W. Savran
SCEC Priorities 6e, 6b, 6c SCEC Groups GMP, CME, GMSV
Report Due Date 03/15/2016 Date Report Submitted 03/16/2016
Project Abstract
 We have used the Support Operator code to simulate ensembles of dynamic rupture models. We have used rough-fault parameters tuned by Shi and Day (2013), as well as elasto-plastic yielding. The simulations are carried out in simple 3-D velocity (halfspace or layered) models, using a grid spacing of 25 m to accurately resolve the break-down zone and wave propagation frequencies up to 10 Hz. We use slip-weakening and rate-and-state friction laws with depth dependent stresses. The dynamic rupture is inserted as a kinematic rupture in AWP-ODC, which allows us to include frequency-dependent anelastic attenuation and small-scale heterogeneities into the ground motion estimates. We compare the ground motion intensities to those from GMPEs, as well as matching the surface slip to the expected values from studies. We find residuals of slip (Δu), peak slip velocity (Vpeak) and rupture velocity (Vrup) to be positively corre-lated with the initial friction (µ0) implying that regions with higher stress-drop (Δτ) produce larger Δu, Vpeak, and Vrup, and vice versa. We also find that maximum correlation for Vrup occurs at a lag distance of ~100 m. This implies that changes in Vrup occur (shortly) after the rupture front has encountered changes in µ0, whereas changes in Δu and Vpeak occur instantaneously. We are on track to complete the rupture generator by the end of SCEC4.
Intellectual Merit SCEC aims to advance seismic hazard analysis to higher frequencies which requires transparent and efficient methods to generate kinematic source functions. Most current kinematic rupture generators have not been tested at the higher frequencies. The proposed rupture generator here includes the energy at the higher frequencies from data-constrained geometrical roughness of the fault, Q(f) and small-scale heterogeneities in the surrounding media.
Broader Impacts Immediate applications of the proposed kinematic rupture generator includes the SDSU Broadband Platform (BBP) method (currently sharing the Graves and Pitarka rupture generator), CyberShake and UCERF3. The project includes training of William Savran and support for his doctoral in the Joint Doctoral Program between SDSU and UCSD.
Exemplary Figure Figure 4. (top) Cross-correlation coefficient between initial friction µ0 and the peak sliprate (Vpeak) residuals computed by removing a depth-dependent mean value for a model with rate-and-state friction law. (bottom) histogram of Vpeak residual values for dynamic rupture simulation using rate-and-state friction and rough fault model. Credit: W.H.Savran.
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