Abstract
We perform earthquake cycle simulations with the goal of studying the characteristics of source scaling relations and strong ground motions in multi-segmented fault ruptures. The 1992 Mw 7.3 Landers earthquake is chosen as a target earthquake to validate our methodology. The model includes the fault geometry for the three-segmented Landers rupture from the SCEC community fault model, extended at both ends to a total length of 200 km, and limited to a depth to 15 km. We assume the faults are governed by rate-and-state (RS) friction, with a heterogeneous, correlated spatial distribution of characteristic weakening distance Dc. Multiple earthquake cycles on this non-planar fault system are modeled with a quasi-dynamic solver based on the boundary element method, substantially accelerated by implementing a hierarchical-matrix method. The resulting seismic ruptures are recomputed using a fully-dynamic solver based on the spectral element method, with the same RS friction law. The simulated earthquakes nucleate on different sections of the fault, and include events similar to the Mw 7.3 Landers earthquake. We obtain slip velocity functions, rupture times and magnitudes that can be compared to seismological observations. The simulated ground motions are validated by comparison of simulated and recorded response spectra.
Highlights
Due to the lack of dense recordings of strong ground motions in the vicinity of faults, numerical modeling is a necessary tool for the assessment of variability of strong ground motions in potentially devastating large earthquakes
Such a set of source models can be used for verification of assumptions underlying strong ground motion simulation schemes (e.g. Irikura and Miyake 2011) and for constraining seismic source inversion
For this work it is desirable to simulate large magnitude events up to Mw 7.8, which are possible on inland faults. With these two aims in mind, we focus this study on the Landers fault system, which hosted the Mw 7.3 1992 Landers earthquake that is used here for validation
Summary
Due to the lack of dense recordings of strong ground motions in the vicinity of faults, numerical modeling is a necessary tool for the assessment of variability of strong ground motions in potentially devastating large earthquakes. A wide range of physics-based models have been used for this purpose. Such modeling includes current knowledge of earthquake source physics, sufficiently accurate simulation of the radiated wave field, and a spatially variable, realistic distribution of near-surface geologic conditions. With the aim of including the physical mechanisms governing the rupture process, kinematic and dynamic rupture modeling has been applied to compute ground motions (Andrews 1976; Dalguer et al 2007; Galvez et al 2016; Ely et al 2010; Olsen et al 1997; Oglesby et al 2012; Ripperger et al 2008; Shi and Day 2013; Wollherr et al 2018)
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