Static stress triggering of Morocco M 6.9 earthquake on 9 September 2023
Objective Coulomb stress change is an important tool for studying earthquake triggering effects and assessing seismic hazard. In order to study the triggering of the static Coulomb Failure Stress(CFS) of the M 6.9 earthquake in Morocco on September 9, 2023, the study determined the geometric config...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Institute of Geomechanics, Chinese Academy of Geological Sciences
2025-02-01
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| Series: | Dizhi lixue xuebao |
| Subjects: | |
| Online Access: | https://journal.geomech.ac.cn//article/doi/10.12090/j.issn.1006-6616.2024039 |
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| Summary: | Objective Coulomb stress change is an important tool for studying earthquake triggering effects and assessing seismic hazard. In order to study the triggering of the static Coulomb Failure Stress(CFS) of the M 6.9 earthquake in Morocco on September 9, 2023, the study determined the geometric configuration and slip properties of the seismogenic fault, analyzed the co-seismic displacement field and surface strain field generated by the earthquake, and evaluated the triggering effects of the mainshock on aftershocks and surrounding faults, revealing the impact of this earthquake on regional seismic activity. Methods Using the "central solution" algorithm, two possible nodal planes of the earthquake were determined, and the local stress field was projected onto these two planes. The nodal plane with higher Coulomb stress was selected as the seismogenic fault plane (strike 253.44°, dip 45.43°, rake 81.05°). Based on statistical formulas, the slip properties of the seismogenic fault plane were determined. Under the homogeneous elastic half-space theoretical model, the co-seismic displacement field and areal strain field of the region were constructed. Subsequently, assuming that the focal mechanisms of the aftershocks on the receiver faults were consistent with the mainshock, the triggering effect of the mainshock on the aftershocks was calculated. Finally, the Coulomb stress changes induced by the mainshock on the surrounding faults were computed to assess the seismic hazard. Results The results show that the material at the epicenter moved outward, while the material on the north and south sides moved inward, resulting in uplift at the epicenter and slight subsidence on the north and south sides. The static Coulomb stress generated by the mainshock promoted the occurrence of most shallow aftershocks, with a large number of aftershocks located in areas of high Coulomb stress change. Additionally, the western and southwestern segments of the South Atlas Fault, the southern segment of the North Atlas Fault, and the western segment of the South Sous Fault all exhibited Coulomb stress change values exceeding the 0.01 MPa threshold, indicating a very high seismic hazard that warrants attention. Conclusion The study demonstrates that the static CFS generated by the M 6.9 earthquake in Morocco significantly influenced the surrounding seismic activity. The mainshock not only promoted the occurrence of aftershocks but also increased the stress on surrounding faults, particularly in the western and southwestern segments of the South Atlas Fault, the southern segment of the North Atlas Fault, and the western segment of the South Sous Fault. [Significance] The study not only assessed the seismic hazard in the region but also provided a foundational dataset for geodynamic research in the area. It contributes to enhancing earthquake monitoring, prediction, and risk mitigation capabilities, promotes the formulation of relevant policies, and safeguards people's lives and property. Therefore, an in-depth exploration of earthquake triggering is of great significance for strengthening post-earthquake scientific research and improving society's ability to respond to earthquakes. |
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| ISSN: | 1006-6616 |