Seismic potential in the southeastern margin of Bayanhar block after 2017 Jiuzhaigou earthquake, China – insight from stress evolution and earthquake probability estimation

Abstract

The southeastern margin of the Bayanhar block (BHB) is located at the junction of the Bayanhar block and the southern China block (SCB). Strong earthquakes occurred frequently in this region because of the intensive tectonic movement. The stress changes caused by strong earthquakes and the observed background seismicity can be used to forecast strong earthquake probability in this region. Therefore, we construct a 3D (three Dimension) viscoelastic finite element model that includes the complex fault system, inhomogeneous medium, tectonic stress, and gravity to simulate the evolutionary stress field when using the observed Global Positioning System (GPS) vectors as the boundary conditions. In addition, we calculate the strong earthquake probability based on the calculated stress and a Poisson probability distribution. The stress evolution result shows the Xianshuihe fault (XSHF), the Huya fault (HYF) and the southern segment except for the Yaan County of Longmenshan fault (LMSF) are located in the stress enhancement area indicating high seismic potential. However, the Minjiang fault (MJF) is located in the stress shadow area. After the Lushan and Jiuzhaigou earthquakes, there is still a high possibility of strong earthquakes in the MJF, HYF, and LMSF zone, according to the strong earthquake probability result.

Keywords:

• Stress evolution
• 3D viscoelastic finite element model
• strong earthquake probability
• southeastern margin of Bayanhar block

Acknowledgements

We appreciate the critical and constructive comments by anonymous reviewers and the Editor that helped us to improve the manuscript.

Author contribution

Liao Li: Conceptualization, Methodology, Software, Visualization, Investigation, Data curation, Writing- Original draft preparation, Writing- Reviewing and Editing. Li Pingen: Conceptualization, Methodology, Software, Visualization, Writing- Reviewing and Editing. Yang Jiansi: Supervision, Writing- Reviewing and Editing. Feng Jianzhou: Visualization.

Disclosure statement

No potential conflict of interest was reported by the authors.

Code availability

The code is available from the corresponding author on reasonable request.

Data availability

The terrain elevation data of ETOPO1, which are released by the U.S. National Geophysical Data Center (http://www.ngdc.noaa.gov/mgg/global/global.html). The observed and inversed stress data which have been used to compare with our simulated stress are obtained from World Stress Map (http://www.world-stress-map.org/data/). The GPS data, Moho Depth, Poisson ratio data are obtained from authors of references which have described detailly in the manuscript. The datasets generated during and/or analyzed in this study are available from the corresponding author on reasonable request.

Additional information

Funding

This study was supported by the National Natural Science Foundation of China (Grant Number. 41674105), the Special Fund of the Institute of Geophysics, China Earthquake Administration (Grants Number DQJB19B27) and Talent startup research grants from National Space Science Center, Chinese Academy of Sciences (Grant Nos. 2023000034, E3RC2TQ4, E3RC2TQ5).