SCEC Award Number 23174 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Co-evolution of earthquakes and fault zones in a fault stepover model
Investigator(s)
Name Organization
Ahmed Elbanna University of Illinois at Urbana-Champaign
Other Participants Md Shumon Mia
SCEC Priorities 2d, 2e, 3d SCEC Groups FARM, SDOT, Seismology
Report Due Date 03/15/2024 Date Report Submitted 11/09/2024
Project Abstract
 Fault zones exhibit multiscale geometric and rheological complexities. A typical fault zone includes some persistent localized zones, generally identified as primarily slip surfaces, within dynamically evolving bulk with both discrete and distributed damage features (Ben-Zion & Sammis, 2003; Mitchell & Faulkner, 2009; Faulker et al., 2010; Lewis & Ben-Zion, 2010). Fault step-overs is an example of geometric complexity that are widely observed in natural fault zones (Wesnousky, 2006; Marliyani et al., 2013; Antoine et al., 2022). They are likely to produce slip complexities through the interaction between adjacent faults. They also naturally couple volumetric and deviatoric deformations due to normal stress fluctuations, bulk plasticity, and slip on multiple surfaces. Furthermore, rupture jumping from one fault to another has the potential to intensify the seismic hazards through larger spatial extent of the rupture and associated higher seismic event magnitude (Harris & Day, 1993; Biasi & Wesnousky, 2016). Moreover, fault zones with stepovers provide a wealth of observations including seismicity, surface deformation, fault network evolution, and off-fault damage (Ben-Zion et al., 2012; Onderdonk et al., 2013; Rockwell, 2021) which represent a unique opportunity for constraining numerical models using multiple streams of data and to improve the predictive power of these models. Here, we propose to develop a computational framework for modeling the co-evolution of fault step-overs and seismicity using a numerically efficient physics-based sequence of earthquakes and aseismic slip simulator. Such approach is poised to uncover new fault zone physics that are hidden from direct observation, through self-consistent numerics, and to improve next generation seismic hazard models by incorporating the dynamically evolving nature of fault zones.
Intellectual Merit Incorporation of off-fault plasticity in the simulation of SEAS provides an avenue to track the evolution of fault zones over aseismic deformation and multiple seismic events. The results show how off-fault plastic deformation may facilitate the rupture jumping in fault zones having tensile stepovers. Previous studies primarily focus on single rupture simulation with elastic bulk which leaves the question open that how the rupture jumping may evolve in a cycle. The rupture jumping observed in this study arises in a consistent manner of cycle simulation which allows heterogeneous evolution of stresses as well as complex seismicity in space and time. The fault network simulation in elastoplastic bulk also shows the multi-cycle evolution of seismicity and fault zone highlighting the connected network of secondary faults through the accumulation of plastic strain. This opens new opportunities for tracking fault zone maturity and understand conditions for slip localization and delocalization. It also suggests that simulations allowing fault growth and creation of new faults may provide an innovative computational pathway for enriching community models such as CFM.
Broader Impacts This proposal partially funded 1 PhD student, Dr. Md Shumon Mia, whose doctoral thesis focused on modeling sequences of earthquakes and aseismic slip in complex fault zones. Dr. Mia graduated in May 2024 and is currently an Assistant Professor at Bangladesh University of Engineering and Technology (BUET). The research conducted as part of this proposal also engaged another graduate student, Chunhui Zhao, who is doing research on damage evolution in fault zones.
Exemplary Figure Figure 3: Figure 3. Evolution of seismicity and fault zone for a random fault network. Migration of seismic and aseismic slip for a random fault network (a, b) The roman numerals indicate the temporal sequence of the events. Fault zone evolution highlighting the connected fault network as depicted by the bi-color plot of the accumulation of plastic strain in c.
Linked Publications

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