Correlation of earthquake source parameters inferred from dynamic rupture simulations

Abstract

[1] We analyzed 315 dynamic strike-slip rupture models computed up to 5.0 Hz to get a quantitative understanding of the correlation and amplitude distributions of parameters describing the earthquake source, such as slip and rupture velocity. To account for the epistemic uncertainty of the problem, we constructed a database of dynamic ruptures computed by ourselves and other authors. This database contains ruptures computed using different models of initial stress, peak stress, and critical slip-weakening distance. Using the set of computed ruptures, we constructed probability density functions (pdfs) for the amplitude distributions of the source parameters and for the correlation between the source parameters. We tried to extract parameter pairs that showed a small variability in the spatial correlation given the large epistemic uncertainty in the input. We only analyzed the areas on the fault with subshear propagation speed. The principal findings are as follows: (1) Final slip amplitude does not show correlation with the local rupture velocity. (2) Final slip amplitude correlates well with risetime. (3) Rupture velocity correlates well with peak slip rate and the duration of the impulsive part of the slip rate function. (4) The pdf of rupture velocity, risetime, and peak slip rate depends on the distance from the nucleation zone. (5) Fracture energy is not the single controlling factor for the rupture velocity; the slope of the linear slip-weakening curve has a significant effect on the rupture velocity. (6) The crack length (length that is slipping at a given time) decreases with the distance from the nucleation zone.

Taxonomy of : A Review of Definitions and Estimation Approaches Targeted to Applications

“…In source studies, removing the attenuation term is fundamental in order to study self-similarity of the source spectrum; this can be done by inverting for the theoretical Q , using empirical Green's functions (EGFs) or multiple EGFs to remove path and site effects, measuring spectral parameters from the coda, or using κ r to correct for high-frequency attenuation (e.g., Irikura, 1986;Abercrombie, 1995;Mayeda and Walter, 1996;Hough, 1997;Lancieri et al, 2012). In the generation of synthetic ground motion using point-source or finite-fault stochastic or hybrid simulation approaches, κ 0 is applied as a low-pass filter to constrain high frequencies, affecting peak ground motion and spectral shape (Boore, 1986;Beresnev and Atkinson,2005;Mai et al, 2010;Schmedes et al, 2010;Foster et al, 2012), imposing such a constraint is necessary to achieve realistic results at high frequencies. The amount of the κ correction in such approaches depends on how Q is incorporated in the TGFs.…”

Rapid Estimation of Damage to Tall Buildings Using Near Real-Time Earthquake and Archived Structural Simulations

“…The rupture process is then allowed to evolve dynamically as dictated by an assumed fault friction law. The development of dynamic source models is an active area of research in earthquake source physics (e.g., Guatteri et al, 2003;Harris et al, 2009;Lapusta and Liu 2009;Schmedes et al, 2010;Bizzarri, 2011;DeDontney et al, 2011). While dynamic source models may better characterize earthquake source physics, the theory is more complex and less mature when compared with kinematic source modeling (e.g., the state of stress in the earth and the fault friction law are not known; they are not as well-constrained as kinematic source parameters such as slip).…”

Strong Ground Motion Estimation

“…The kinematic rupture model used here enforces correlations between these parameters by using a common fractal seed to specify relationships between all these fault rupture parameters. Oglesby and Day (2002), Guatteri et al (2003), and Schmedes et al (2010) used dynamic rupture simulations to demonstrate that rupture parameter correlation, as implemented in the stochastic kinematic rupture model outlined here, is necessary to produce realistic source parameters for ground motion estimation. The fault slip variability incorporates the natural log standard deviation of strike-slip displacement observed by Petersen et al (2011) in their analyses of global measurements of strike-slip fault displacements.…”

“…The kinematic model used here produces slip models with 1/k 2 (k is wavenumber) distributions consistent with estimates of earthquake slip distributions (Somerville et al, 1999) and  2 ( is angular frequency) displacement spectra in the far-field. Oglesby and Day (2002) and Schmedes et al (2010) used numerical simulations of dynamic fault rupture to show that rupture velocity, rise time, and slip are correlated with fault strength and stress drop, as well as each other. The kinematic rupture model used here enforces correlations between these parameters by using a common fractal seed to specify relationships between all these fault rupture parameters.…”