Chang Liua,b, Yaolin Shi c
aState Key Laboratory of Marine Geology, Tongji University, Shanghai, China
bShanghai Sheshan National Geophysical Observatory, China
cKey Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing, China
Abstract
Over the past 50 years, a sequence of destructive earthquakes, such as the 1968 (Mw 7.2), 1996 Tonimi (Mw 7.9), and 2018 Palu (Mw 7.5) earthquakes, occurred on the Palu-Koro strike-slip fault and the Minahassa Megathrust, which caused catastrophic disasters in Central Sulawesi, Indonesia. To explore the relationship between fault interaction and earthquake migration in this target area, we simulated the Coulomb stress change (ΔCFS) caused by 13 historical large earthquakes (M ≥ 6.0) since 1968. We show that the 1968 earthquake (Mw 7.2) on the Palu-Koro Fault promoted the 1996 earthquake sequence (Mw 7.9, Mw 6.6, and Mw 7.0) on the Minahassa Megathrust by transferring positive stress to its western edge with a maximum ΔCFS value of 124 kPa before 1996. Consequently, the 1996 earthquake (Mw 7.9) promoted six large earthquakes (M ≥ 6.0) including the 2018 Palu earthquake (Mw 7.5) on the Palu-Koro Fault between 1998 and 2020 via stress loading over the entire Palu-Koro Fault with a maximum ΔCFS value of 76 kPa. Via a positive feedback, these six earthquakes have increased stress at the western edge of the Minahassa Megathrust with a maximum ΔCFS value of 265 kPa up to 2020, resulting in increased seismic and consequent tsunami hazards in this region. Based on these risks, close attention should be paid to the future seismic hazards in Central Sulawesi. These findings suggest that the Palu-Koro Fault and the Minahassa Megathrust constitute a coupled fault system in which seismicity in either fault might bring the other closer to failure. Our results provide new insights into the causes of earthquake generation, migration, and hazard estimation in Central Sulawesi, and provide a basis for understanding stress transfer and seismic activity in strike-slip and thrust fault systems globally.
FullArticle:https://www.sciencedirect.com/science/article/pii/S0040195122003249?via%3Dihub
