SCEC Award Number 10202 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Interaction of dynamic earthquake ruptures with fault heterogeneity over many earthquake cycles
Investigator(s)
Name Organization
Nadia Lapusta California Institute of Technology
Other Participants Graduate student Junle Jiang
SCEC Priorities A10, B1, A8 SCEC Groups FARM
Report Due Date 02/28/2011 Date Report Submitted N/A
Project Abstract
 N/A
Intellectual Merit The main goal of this work is to study how dynamic rupture interacts with fault heterogeneity over many earthquake cycles, taking into account the effect of prior fault slip. Dynamic rupture simulations suggest that both variations in fault strength and fault prestress can strongly influence the development of dynamic ruptures, e.g. induce or suppress supershear rupture speeds (e.g., Day, 1982; Madariaga et al., 1998; Madariaga and Olsen, 2000; Fukuyama and Olsen, 2002; Dunham et al., 2003; Liu and Lapusta, 2008). The two distributions – of fault strength and shear stress – are typically assumed independently, but they are related due to prior fault slip. To assess how the distribution of fault strength affects typical fault prestress before large events, we simulate long-term slip on a fault segment that includes earthquake cycles and (i) resolves all the stages of every single earthquake in detail, including earthquake nucleation, dynamic rupture propagation and arrest, and (ii) reproduces post-seismic slippage and interseismic creep (Lapusta et al., 2000; Lapusta and Liu, 2009; based on Dieterich, 1979, 1981; Ruina, 1983; Geubelle and Rice, 1995; Ben-Zion and Rice, 1997). Our simulations of faults with heterogeneous normal stress distributions motivated by non-planar faults (Jiang and Lapusta, AGU, 2010; Jiang and Lapusta, 2011, manuscript in preparation) show that the RMS mismatch between the representative static fault strength and prestress before model-spanning events evolves to near-constant value in the long-term history of the fault. Quantifying this long-term mismatch in terms of the model parameters, such as the degree of fault heterogeneity, should provide guidance for assigning initial conditions in simulation of single dynamic ruptures. In a set of models, comparison between the first simulated earthquake and subsequent events shows that shear stress redistribution over time at least partially compensates for the heterogeneity in fault strength, diminishing its effect on seismic events.
Broader Impacts Large-scale dynamic rupture simulations carried out by SCEC teams have the potential to provide novel and critical information for the assessment of seismic hazard in Southern California. The results of this project, when further developed, would suggest ways of assigning initial conditions for these simulations consistent with other assumed ingredients such as the fault strength heterogeneity. A student and a postdoctoral fellow has gained valuable research experience by participating in the project and interacting with the SCEC community.
Exemplary Figure N/A
Linked Publications

Add missing publication or edit citation shown. Enter the SCEC project ID to link publication.