Elastic and frictional controls on time-variable slip rates in a two-fault system
Alba M. Rodriguez Padilla, Alexis Saez, Jean-Philippe Avouac, Kyungjae Im, & Hojjat KavehSubmitted September 8, 2024, SCEC Contribution #13748, 2024 SCEC Annual Meeting Poster #128
Paleoseismic data shows that parallel faults can trade-off slip over time, resulting in time-variable slip rates. Previous work has hypothesized that such behavior can emerge from changes in the tectonic loading rate, time-variable fault strength, time-dependent loading from ductile shear zones, and phase locking of faults in their late interseismic stage. Here, we use open-source quasi-dynamic earthquake simulator Quake-DFN to model fault loading and release in time-scales comparable to those recorded in the geologic record. We model a two-fault system governed by rate and state friction, where both faults are identical in dimensions and frictional parameters, with complete overlap, and we vary the spacing between the two faults and the nucleation size (∝Dc). Our models demonstrate the interevent time and magnitude variability that emerges from the elastic interactions between the faults, controlled by the fault spacing, and from the stress heterogeneity on each fault, controlled by the nucleation size. These two competing effects result in several distinct regimes: steady-state creep, time-variable creep events on alternating faults, synchronous and asynchronous periodic full ruptures, and chaotic partial ruptures. Models with sub-centimeter-scale Dc and faults closer than 10 km apart yield time-variable slip rates where partial ruptures on one of the faults cause the faults to trade-off in accommodating the majority of the seismic moment for a few centuries.
Citation
Rodriguez Padilla, A. M., Saez, A., Avouac, J., Im, K., & Kaveh, H. (2024, 09). Elastic and frictional controls on time-variable slip rates in a two-fault system. Poster Presentation at 2024 SCEC Annual Meeting.
Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)
