# Coseismic Stress Change and Viscoelastic Relaxation after the 2008 Great Sichuan Earthquake
## 5 Conclusions  
In this study, the long-term stress evolution due to coseismic stress and postseismic viscoelastic relaxation is calculated based on the Mohr-Coulomb failure criterion in Sichuan Province and adjacent regions in China; the events studied are the 2008 Ms 8.0 Wenchuan \begin{table}
\begin{tabular}{c c c c c c} \hline  & **Mode 1** & **Mode 2** & **Mode 3** & \(\mu^{\prime}\) = **0.2** & \(\mu^{\prime}\) = **0.4** & \(\mu^{\prime}\) = **0.6** \\ \hline Stress Change & 0.036238 & 0.036271 & 0.036276 & 0.0477 & 0.0419 & 0.0362 \\ (MPa) & & & & & \\ \hline \end{tabular}
\end{table} 
Table 6: Stress changes according to different models and different friction coefficients. \begin{table}
\begin{tabular}{c c c c} \hline  & **Model 1** & **Mode 2** & **Mode 3** \\ \cline{2-4}
**Layer** & **\(\eta\) (Pa-s)** & \(\eta\) (Pa-s)** & \(\eta\) (Pa-s) \\ \hline
1 & - & - & - & - \\
2 & - & - & - & - \\
3 & \(1.0\times 10^{19}\) & \(1.0\times 10^{21}\) & \(1.0\times 10^{17}\) \\
4 & \(5.0\times 10^{19}\) & \(5.0\times 10^{21}\) & \(5.0\times 10^{17}\) \\
5 & \(1.0\times 10^{18}\) & \(1.0\times 10^{20}\) & \(1.0\times 10^{16}\) \\
6 & \(1.0\times 10^{18}\) & \(1.0\times 10^{20}\) & \(1.0\times 10^{16}\) \\ \hline \end{tabular}
\end{table} 
Table 5: Models used to analyze the effect of different combinations of viscosities for both the upper mantle and lower crust. Model 1 is the original model used in this work. Model 2 has the maximum value of the viscosity combination. Model 3 has the minimum value of the viscosity combination. earthquake, the 2010 Ms 7.1 Yushu earthquake, the 2013 Ms 7.0 Lushan earthquake, the 2014 Ms 6.3 and Ms 5.8 Kangding earthquakes, and the 2017 Ms 7.0 Jiazhaigou earthquake. The stress changes due to viscoelastic relaxation over the past 10+ years are analyzed to systematically track the evolution of postseismic stress changes, as well as the potential earthquake hazard in the study area. The results show the following:  
1. The spatial distribution of coseismic stress changes corresponds with the spatial pattern of aftershocks for these major events. The coseismic stress changes caused by these earthquakes have a fundamental triggering effect on subsequent earthquakes. 2. The postseismic relaxation effect leads to increased \(\Delta\)CFS near the northern and southern edges of the Longmenshan fault. Comparing the coseismic and postseismic stress changes, the Wenchuan earthquake caused larger amounts of coseismic stress change than other earthquakes. 3. The northern and southern segments of the Longmenshan fault, the east Kunlun fault, the southern segment of the Xianshuihe fault, the northern segment of the Huya fault, and the Huayingshan fault are obviously affected by the stress increases caused by these mainshocks. In particular, the northern and southern Longmenshan fault zones are located in areas of increasing stress concentration and might be the areas with the greatest seismic risk in the future. [PERSON] designed the study, performed the modeling, and interpreted the results. [PERSON], [PERSON] and [PERSON] wrote the manuscript. [PERSON], [PERSON], [PERSON] and A.L. provided comments to improve the manuscript. All authors discussed the results and interpretations and participated in writing the paper. All authors have read and agreed to the published version of the manuscript. This study was supported by the National Natural Science Foundation of China (Grant No. 41964001), the Second Tibetan Plateau Scientific Expedition and Research Program (2019 QZKK0708), the State Key Laboratory of Earthquake Dynamics (Project No. LED2019B04), and the CAS Pioneer Hundred Talents Program. Not applicable. Data Availability StatementData are available in the figures and tables or from the authors upon reasonable request. We are grateful to [PERSON], [PERSON], [PERSON], and [PERSON] for their shared data and constructive comments. We thank [PERSON] from the Geological Survey of Japan for sharing the GeoTao s software used for the calculation and plotting in this study.