Fig. 9

A schematic evolutionary model of the Palu–Koro Fault in NW Palu Valley with age of abandonments for two alluvial fan units from Bellier et al. (1999). a Deposition of old alluvial fans, controlled by a basin-bounding fault, which has a major normal slip component. This phase may end at 120 kya. b The episode of later normal faulting in the east, triggered the deposition of young alluvial fans, which truncated against the old alluvial fans. These alluvial fans were displaced at 11 kya. c Later deformation is dominated by strike–slip faulting. A series of N–S ridges uplifted distal parts of some young alluvial fans and may be associated with transpression deformation. This strike–slip fault was ruptured during the 2018 Palu earthquake