A CASE STUDY: VELOCITY OF LIQUEFACTIONINDUCED LANDSLIDE IN JONO-OGE TRIGGERED BY 7.5 Mw PALU EARTHQUAKE

摘要

On the 28th of September 2018, a 7.5 Mw earthquake in Palu, Indonesia, triggered multiple phenomenaevents such as liquefaction, landslide, and tsunami. One unique video recorded the landslide in Jono-Oge,located near Palu Valley, captured by a local citizen from his house that was carried along by a debris flow.The video shows that the land moved like water, carrying buildings and trees while some structures remained.The moving camera raises difficulties for the analysis because it operates with various degrees ofmovement. However, the velocity estimation is possible by applying two types of camera angle analysisusing non-moving buildings captured on the video as the point of reference. In this case, a red roof houseand steel tower. We identified that the camera moved from east to west and started from elevation 70 m,located 1000 meters from the top of the Jono-Oge landslide at the irrigation canal. At elevation 68 m, thelandslide velocity was 5.1 m/s and slowed down to 4 m/s after moving 200 meters to elevation 62 m. Thisdeceleration might correspond to the decrease in slope inclination, from 3% to a gentler slope of only 1%.This result will be informative for the setting of landslide and landslide-induced tsunami simulation.