Galih A Prayitno, - and Muhsiung Chang, - and Togani C Upomo, - and Renchung Huang, - and Rini Kusumawardani, FT Teknik Sipil (2020) Onsite Observations of Petobo Liquefaction Area due to 2018.9.28 Palu-Donggala, Indonesia Earthquake. In: f the 18th Conference on Current Researches Geotechnical Engineering, September 1-3, 2020, Taiwan.

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Abstract

Liquefaction-induced flowslides occurred in several places of Palu City, in the Central Sulawesi of Indonesia, due to Palu-Donggala earthquake with a magnitude (Mw) 7.5 on September 28, 2018. One of the landslides was in Petobo Village, which is close to Mutiara SIS Al-Jufrie Airport of the city. Petobo landslide, with an area of approximately 1.64 km2 , has caused most fatalities among other areas affected by this earthquake. To have a better understanding of the flowslide, onsite observations through witness interviews, drone photos and site mapping have been conducted in the early of 2020. Additional information from satellite images and Google Street views are also compared with the onsite observations. The study reveals that Petobo landslide could possibly be divided into four types of morphology. Ground slip (GS) is due to a sudden loss of support and results in cracks and soil blocks. Lateral spread (LS) is characterized by a series of parallel cracks and earthen ridges as a result of lateral spreading and shaking. Liquefaction flow (LF) occurs in the liquefied ground after the shaking. The gravitational driving shears, if sufficient large enough, would move the liquefied ground for a large distance. Debris flow (DF) is similar to LF, with the difference that the existing ground is not liquefied but deposited with debris from the upstream side.

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