Simulation of the Jiuzhaigou, China, earthquake by stochastic finite-fault method based on variable stress drop
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Simulation of the Jiuzhaigou, China, earthquake by stochastic finite‑fault method based on variable stress drop Pengfei Dang1 · Qifang Liu2 · Jian Song1 Received: 24 January 2020 / Accepted: 19 May 2020 © Springer Nature B.V. 2020
Abstract An improved stochastic finite-fault method was used to simulate the Mw 6.6 earthquake that occurred on August 8, 2017, in Jiuzhaigou, Sichuan, China. A variation of the stochastic finite-fault method, considering the dynamic corner frequency, was used to overcome the corner frequency. It explains the effect of a given slip distribution on the corner frequency of each subfault. A comparison of the response spectra (damping ratio 5%), spectral ratio (simulated values/observed values), and model deviation demonstrated that the improved corner frequency performs well for the whole periods, especially in short periods from 0.2 to 1 s. Similarly, the revised duration model and the site-amplification factor were applied to simulate the ground motion during the Jiuzhaigou earthquake, and then the response spectra were obtained. The duration of the nine near-field station recordings matched well with the simulated ground motions, and the peak ground acceleration (PGA) of most of the stations matched well with the observed PGA. In the short periods (T 40km) 0.05–10 5% / 1 f0 +0.1R 0.8 × (shear-wave velocity) Western North America generic rock site
180f 0.45
Beresnev and Atkinson (1998b)
122°/40° 5–21 6.7 50 18 by 24 3 2.8, 3.7 1.3 × 1026 0.035
Fault orientation (strike, dip)
Depth of top (km) Moment magnitude Average stress drop (bars) Fault dimensions along strike and dip (km) Subfault dimensions (km) Shear-wave density (g/cm3), velocity (km/s) Mainshock moment (dyne-cm) Kappa (s) Quality factor
Motazedian and Atkinson (2005) Atkinson and Boore (2006)
Wang et al. (2015)
This study
Wang et al. (2015)
Beresnev and Atkinson (1998b) USGS Beresnev and Atkinson (1998b) Zheng et al. (2017) Wang et al. (2015) Beresnev and Atkinson (1998b) Beresnev and Atkinson (1998b) Wang et al. (2015) Wang et al. (2015)
References
Parameter value
Parameter
Table 2 Modeling parameters for simulation of Northbridge earthquake
Natural Hazards
13
Natural Hazards
Fig. 2 Spectral ratio for the modeling results obtained by the approach of Motazedian and Atkinson (2005) and the enhanced method proposed in this study. Each panel also shows mean ratio ± one standard deviation (dashed lines) and 95% confidence interval of the mean (shaded area)
Fig. 2, which is better as compared to model 1 for the same periods. This validates the effectiveness of the improved model.
4 Simulation of the 2017 Jiuzhaigou earthquake 4.1 Source model and input parameters The fault plane (Strike, dip = 151°/85°) extending along the northwest direction of the body wave focal mechanism solution is considered as the actual fault plane according to the USGS. The thickness of the crust in Jiuzhaigou is about 50 km (Bassin et al. 2000; Wen et al. 2015; Zheng et al. 2017). Considering that the potential rupture can
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