Impact of rupture complexity on seismic hazard: Case of the 2018 Mw7.5 Palu earthquake

Rupture complexity results in difficulty in quantifying seismic hazards, such as the probability of an earthquake on multiple fault segments and spatial distribution of fault displacement on the surface. Here we tried to propose a dynamic model to fit the rupture behavior of the 2018 Mw7.5 Palu earthquake, which splays along several sub-fault plans on the surface. The Palu event was initiated on an unknown fault and propagated on a curved plane on the Palu-Koro and Matano faults. According to the Interferometric Synthetic Aperture Radar (InSAR) data, both principal (on-fault) and distributed (off-fault) faulting were identified and spatial displacement on the surface could be evaluated. To model the complex geometry of the coseismic rupture plane and corresponding deformation, we proposed a dynamic model through the Discrete Element Method (DEM). Our model demonstrated rupture along a planar fault at depth and several splay faulting with various deformations on the surface, corresponding to the observations. The simulations represented temporal rupture behavior that covers several earthquake cycles and the probability of superficial fault displacement, which shed light on subsequent seismic hazard assessment and probabilistic fault displacement hazard analysis, respectively.