The 2021 Mw 7.3 Maduo earthquake ruptured the Kunlun Pass‐Jiangcuo fault (KPJF) in the Bayan Har Block (BHB) in northeastern Tibet. To explore the reasons behind the Maduo earthquake and the seismic hazards that followed this event in the BHB, we simulated the Coulomb stress changes before and after 2021 caused by 27 large historical earthquakes in the past centuries. We found that the Maduo earthquake was delayed for approximately 157 years because of the stress shadow resulting from fault interaction in the BHB. This stress shadow was mainly controlled by the 1937 Mw 7.5 earthquake on the Eastern Kunlun fault (EKLF) and the 1947 Mw 7.75 earthquake on the Dari fault. The stress shadow created by the Maduo earthquake covered several strike‐slip faults surrounding the Maduo earthquake rupture through negative feedback. Future seismic activity in the stress shadow zone may be delayed to a certain extent. Based on this finding, we propose that earthquakes on a fault might inhibit earthquakes on surrounding faults in parallel strike‐slip fault systems by creating a shadow zone in the BHB. This finding is important for understanding earthquake generation and migration in northeastern Tibet. It is also helpful for understanding the fault interactions in similar fault systems globally. The seismic hazards of the seismic gap to the west of the KPJF and the Maqin‐Maqu seismic gap on the EKLF increased after the Maduo earthquake. Therefore, attention should be paid to hazards prevention in these regions.
Earthquake interaction across multiple time scales can reveal complex stress evolution and rupture patterns. Here, we investigate the stress change's role in the 2023 Mw 7.8 and 7.6 earthquake doublet along the Eastern Anatolian Fault (EAF), using simulations of 21 historical earthquakes (M ≥ 6.1) from 1822 to 2023. Focusing on six cascading sub-events during the 2023 Kahramanmaraş Earthquake Sequence, we reveal how one sub-event's stress alteration can impact the emergence and rupture dynamics of subsequent sub-events. Our analysis unveils that the 2023 Mw 7.8 earthquake was deferred by 52 years due to stress shadow effects from historical events, while the 2023 Mw 7.6 earthquake was accelerated by 26 years as a result of stress increases from historical events and ultimately triggered by the 2023 Mw 7.8 earthquake. This study underscores the importance of grasping earthquake preparation, rupture initiation, and propagation in the context of intricate fault systems worldwide. Based on these results, we draw attention to heightened seismic hazards in the Elazig-Bingol seismic gap of the EAF and the northern section of the Dead Sea Fault, necessitating increased monitoring and preparedness efforts.
The Mw 7.5 Palu earthquake struck the Palu-Koro fault on September 28, 2018 in the Sulawesi Island, Indonesia. Previous studies suggested that the predominantly unilateral southward rupture of this earthquake unzipped the central part of the Palu-Koro fault. Two seismic gaps were left to the north and south ends of the Palu-Koro fault. To date, the cause for earthquake generation has yet to be investigated. As a result, the reasons behind the earthquake rupture's southward unilateral propagation and termination remain unclear. The hazards of the two seismic gaps at the north and south ends of the Palu-Koro fault have yet to be explored. As such, the present study calculated the Coulomb stress change that was induced by historical large earthquakes within the target region. The stress partition and evolution on the Palu-Koro fault were examined before and after the 2018 Palu earthquake. We found that the 1996 earthquake (Mw = 7.9) on the Minahassa thrust triggered the 2018 Palu earthquake by promoting stress at the epicenter of the 2018 earthquake. The stress shadow close to the north of the epicenter of the earthquake acted as a stress barrier by preventing the earthquake northward rupture. However, the southward earthquake propagation was terminated by the stress shadow to the south of the rupture. These stress shadows were caused by the historical earthquakes on the Palu-Koro fault. Stress promotions in the two seismic gaps of the Palu-Koro fault produced by 2018 Palu earthquake have resulted in increased seismic and tsunami hazards, calling close attention to hazard prevention in central Sulawesi. Our results are important for understanding the stress migration and the induced seismic activity in the thrust and strike-slip faults system globally.
The west-east trending strike-slip Qilian-Haiyuan fault system is located in the northern margin of Qilian orogen in northeastern Tibet. It extends approximately 1,000 km from the west near the Hala Lake to the east of Guyuan county in Gansu province, China (Yang et al., 2022). This fault system is composed of several fault segments:
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