Additional file 1 of A systematic scheme to develop dynamic earthquake rupture scenarios: a case study on the Wenchuan–Maoxian Fault in the Longmen Shan, China, thrust belt
Creators: name: Tang, Rongjiang
name: Ando, Ryosuke
Publisher: name: figshare
Year: 2024
Subjects: subject: Geology
subject: FOS: Earth and related environmental sciences
subject: Geophysics

description: Additional file 1: Text S1. Stress inversion. Text S2. Test on parameters for fault geometry inversion. Text S3. The effect from Wenchuan mainshock . Appendix A. Conjugate gradient method for fault geometry inversion. Text S4. Peak ground displacement and velocity. Figure S1. Map showing the setting of major faults of the center Longmen Shan fault zone. The red bold black lines indicate the field-confirmed rupture traces in Wenchuan earthquake (Xu et al. 2009; Liu-Zeng et al. 2009). The blue solid and dotted lines represent the WMF and Lixian faults, both of which did not slip in the main shock but are very active in aftershocks. Accurate fault trace of the WMF is from the field investigation by Xie et al (2011), and the location of the LXF trace is from the distribution of aftershocks (Yin et al. 2018; Li et al. 2019). “Beach ball” represents the lower hemisphere projection of the focal mechanism (strike 225°/dip 39°/rake 120°) of the $${M}_{w} 7.9$$ M w 7.9 ( $${M}_{s} 8.0$$ M s 8.0 ) Wenchuan earthquake obtained from Zhang (2009). Pink circles—historic strong earthquakes (Before 2008) larger than M5. Yellow circles— historic strong earthquakes (Before 2008) with magnitude $$4\le M&lt;5$$ 4 ≤ M &lt; 5 . The white arrow indicates block motion direction. CD—Chengdu; DY—Dayi; YX—Yingxiu; WC—Wenchuan; LX—Lixian; MX—Maoxian; BC—Beichuan; NB—Nanba. Figure S2. Seismicity following the 2008 Wenchuan earthquake plotted in the along-strike distances (a) and cross-section along the purple box (b). Figure S3. Boundary elements for each fault segment and free surface. We employed the boundary elements of approximately 26,824, and control triangular elements to be 500 m on the fault and free surface in the vicinity of the fault, and increase this size with a maximum rate of 7.5 times toward the outer boundary of the surface until it reaches the maximum size of around 2000 m. Figure S4. Initial on-fault shear stress and normal stress resolved by the tectonic stress, as well as Initial on-fault shear stress drop $$\tau_{drop} = \tau_{0} - \mu_{d} \sigma ,$$ τ drop = τ 0 - μ d σ , μd = 0.12. Figure S5. a The spatial distribution of 391 focal mechanism solutions (beachball, lower hemisphere stereographic projection) determined in this study from earthquakes between 2009 and 2016. The color and size of the beachballs indicate the type and seismic moment, respectively. Red, normal (NF) or normal oblique faulting (NS); green, strike-slip faulting (SS); blue, thrust (TF) or thrust oblique faulting (TS); black, mixed type. b Histogram illustrating the faulting type distribution of the earthquake focal mechanism data determined in this study. (From Li et al. 2019). Figure S6. Inferred regional stress field. a The trade-off between model length and data misfit, e = 1.6 is selected to be the optimal damping parameter. b An example to show the distribution of Closeness between best stress tensor and inverted stress tensors from 1000 times bootstraps in grid number 1. To estimate the stress uncertainty with 95% confidence, we pick 95% of them that have the highest scalar product with the best stress tensor. c Results of crustal stress field inversion from 440 fault plane solutions for the Longmen Shan region with a grid interval of 0.2° both in longitude and latitude (only the stresses in our calculation domain are shown). d The principal stress axes obtained in each block are denoted by red ( $${\sigma }_{1}$$ σ 1 ), blue ( $${\sigma }_{2}$$ σ 2 ) and green ( $${\sigma }_{3}$$ σ 3 ) in the lower hemisphere stereonet. Figure S7. Along strike distribution of scaled three-component principal stress. The scaled three-component principal stress are marked red ( $${\sigma }_{1}$$ σ 1 ), blue ( $${\sigma }_{2}$$ σ 2 ) and green ( $${\sigma }_{3}$$ σ 3 ) colors, which are derived using bootstrap resampling of the selected fault planes. The black circles denote the stress component closest to the vertical, and the dotted lines are the average of each stress component (a). The orange solid line and red dash line represent the trend and average of principal stress orientation (b). Figure S8. Inversions of fault geometry with different horizontal intervals of interpolated curves. From top to bottom: Observed long-term slip rates and scaled traction; Distribution of inverted parameters $$\eta$$ η ; Objective functions versus iterations; Final fault surface derived from inverted parameters $$\eta$$ η . Other details for each plot refer to Fig. 4. Figure S9. Same as Additional file 1: Fig. S7, but with different integral radius. Figure S10. Same as Additional file 1: Fig. S7, but with regularization parameters. Figure S11. a Calculated Coulomb failure stress change and the movement of Lixian Fault, assuming $${\mu }_{s}=0.52$$ μ s = 0.52 (Modified from Tang et al. 2021a, b). The spatial distribution of aftershocks is from Yin et al. (2018). b The Coulomb stress change of the WMF, assuming that the LXF ruptures at southern end. Figure S12. Three components and magnitude of surface slip, with eastern and western nucleation points. The white pentagrams denote the epicenter. The white arrow indicates the NE direction. See Fig. 5 for the definition of the x-y-z components. Figure S13. Magnitude of peak ground velocities from different nucleation points. The white pentagrams denote the epicenter. Figure A1. Schematic to describe the calculation of traction from interpolated fault surface. Green circles are the control points at equal intervals on the dip curves, and orange circles denote the equally spaced points on the interpolation curves. The average interval of collocation points is around 3 km. The inverted triangles represent the locations of the measured points.