Landslides triggered by the 2018 Mw 7.5 Palu supershear earthquake in Indonesia

Abstract

On September 28th, 2018, a supershear earthquake of moment magnitude (Mw) 7.5 struck the Palu area in central Sulawesi, Indonesia. To gain insight into landslides triggered by the Palu earthquake, a detailed landslide interpretation project was carried out in the meizoseismal area. To establish a co-seismic landslide inventory, we collected high-resolution images, including Worldview pre- and post- earthquake images, Sentinel pre- and post- earthquake images and Google Earth pre- and post- earthquake images. The results show that the Palu event triggered at least 7063 co-seismic landslides, including 8 flowslides. The total landslide area is 29.7 km2, with the highest density being 96 landslides/km2. The rock type (Kambuno granite) is a dominant factor influencing the landslide distribution; the average landslide H/L (H is the fall height and L is the horizontal length of an entire landslide) is 0.56. The flowslides that occurred in the Palu Basin are seismic liquefaction-induced landslides that failed along very gentle slopes (generally, slopes that are <3°) and traveled hundreds to thousands of meters, and the average H/L was 0.021.