Geotechnical damage in the 2018 Sulawesi earthquake, Indonesia

Abstract

Background: On September 28th, 2018, at 18:02 local time (10:02 UTC), a strong earthquake of magnitude Mw = 7. 5 struck Central Sulawesi Province, Indonesia. The epicenter was located at 0.256 o south latitude and 119.846 o east longitude, around 77 km from Palu city, and 20 km below the ground surface. To understand the damage caused by the earthquake, and find a solution to mitigate the geo-disasters in Indonesia, a preliminary investigation on the 2018 Sulawesi earthquake was conducted from 16 to 20 November 2018. This quick report focuses on ground displacements induced by fault movement and large-scale ground flow. Results: During the survey, there is some geotechnical damage were found, such as ground displacement induced by fault movement, liquefaction, landslides, and large-scale ground flow in some certain areas. Large ground displacement was found in some particular areas, such as Kedondong, Pipa Air, Pangeran Diponegoro and Cemara streets in Palu city. The earthquake also triggered large-scale ground flow in some different sites, such as Balaroa and Petobo districts in Palu city and Jono Oge and Sibalaya Villages. Conclusions: The locations of large ground displacements appeared at surface coincide well with the estimated fault line. Therefore the large ground displacements were seems to be induced by the fault movement. Large ground flow caused severe damage to not only human but also houses and buildings. The mechanism of the large ground flow should be clarified in near future.

New High-Resolution Modeling of the 2018 Palu Tsunami, Based on Supershear Earthquake Mechanisms and Mapped Coastal Landslides, Supports a Dual Source

“…The 2018 rupture was supershear (Bao et al, 2019;Socquet et al, 2019;Fang et al, 2019) (i.e., it propagated faster along the fault than the local shear wave velocity), and the resulting ground motions caused widespread damage throughout the western Central Sulawesi region. Inland, the earthquake triggered landslides and induced considerable liquefaction that resulted in major destruction and numerous fatalities (Bradley et al, 2019;Watkinson and Hall, 2019;Miyajima et al, 2019). From eyewitness accounts and video evidence (Sassa and Takagawa, 2019), almost immediately after the earthquake, numerous coastal areas along Palu Bay experienced landslides (see locations of main ones marked LS-in Figure 1B), which were rapidly followed by destructive tsunami waves (Arikawa et al, 2018;Carvajal et al, 2019).…”

Impact of Landslides Induced by the 2018 Palu Earthquake on Flash Flood in Bangga River Basin, Sulawesi, Indonesia

“…The shallow tectonic earthquake of magnitude 7.5 on September 28, 2018 in Palu, Central Sulawesi, Indonesia not only caused damage to the basic infrastructures, but also triggered three types of secondary disasters, namely tsunami, liquefaction and landslide (Bao et al, 2019;Carvajal et al, 2019;Miyajima et al, 2019;Bradley et al, 2019). The three types of those disasters have basically caused the same impact as an earthquake, in addition to fatalities in very large numbers.…”

Report on the UNESCO Chair workshop on geoenvironmental disaster reduction 28th April - 1st may, 2019, Palu - Jakarta, Indonesia

“…The geological feature is similar with the previous location, which comprises of mainly sediment deposit from alluvial and colluvial fan. The area has gentle slope with an average of 1.9% slope (Miyajima et al, 2019). However, the ground flow travel distance is interestingly the furthest among the other similar prone areas.…”

“…1). The road and houses were dragged about 350 m to the West due to ground flow (Miyajima et al, 2019). Figure 2 shows the path of ground flow in the village.…”