Space‐Time Stress Variations on the Palu‐Koro Fault Impacting the 2018 Mw 7.5 Palu Earthquake and Its Seismic Hazards

Abstract

AbstractIn this study, we calculated the Coulomb stress change before and after the 2018 Palu earthquake (Mw 7.5) induced by historical large earthquakes on and around the Palu‐Koro fault (PKF) within Sulawesi Island, Indonesia. We found that the 1996 earthquake (Mw 7.9) on the Minahassa thrust likely promoted the 2018 Palu earthquake by stress loading on its hypocenter. Stress shadows in the PKF impacted the 2018 earthquake rupture’s southward unilateral propagation and termination. Stress increases in the two seismic gaps to the north and south ends of the PKF have resulted in increased seismic hazards, calling close attention to hazard prevention in central Sulawesi. This indicates that fault‐interaction‐induced stress variations on the PKF significantly controlled the 2018 Palu earthquake and its seismic hazards. Our study is important for understanding stress triggering between the subduction earthquakes and intraplate earthquakes in thrust and strike‐slip faults systems globally.