Stress Transfer at the Northeastern End of the Bayan Har Block and Its Implications for Seismic Hazards: Insights From Numerical Simulations

Abstract

Abstract The 2021 Mw 7.4 Maduo earthquake in Qinghai, China, filled the seismic gap in the eastern segment of the northern boundary of the Bayan Har Block, and four other M > 7 historical strong earthquakes occurred at the northeastern end of the Bayan Har Block within a period of 80 years before the Maduo earthquake. This series of large seismic events provides an excellent example for investigating the stress transfer and fault interactions of strong earthquakes on the continent. In this study, we established a viscoelastic numerical model to calculate the stress transfer before and after the 2021 Maduo earthquake produced by historical earthquakes at the northeastern end of the Bayan Har Block. We found that the Maduo earthquake occurred in the Coulomb stress shadow zone caused by the historical earthquakes, and the 1947 Dari earthquake and the 1937 Tuosuo Lake earthquake jointly delayed the occurrence of the Maduo earthquake. The stress transfer of five M > 7 earthquakes to the surrounding faults after 1937 resulted in the segments at both ends of the Dari fault that were unruptured in the 1947 earthquake, the East Kunlun fault zone west of Alan Lake, the Maqin‐Maqu segment of the East Kunlun fault zone, the Longriba fault, the segment of the Ganzi‐Yushu fault south of Yushu, the Minjiang fault, and the northern segment of the Xianshuihe fault being located in the Coulomb stress loading zone. Sustained attention should be paid to the block boundary faults and intra‐block faults with increased seismic hazards.

Keywords

• Maduo earthquake
• finite element method
• viscoelastic relaxation
• interseismic loading
• Coulomb stress change
• seismic hazards