Cascading Geological Hazards and Risks of the 2018 Sulawesi Indonesia Earthquake and Sensitivity Analysis of Tsunami Inundation Simulations

Abstract

Multiple cascading hazards triggered by the 2018 Sulawesi, Indonesia, earthquake caused various compounding consequences. A major strike-slip fault movement with along-dip components resulted in intense ground shaking, liquefaction and lateral spreading, large-scale mudflows, and tsunamis. This paper presents observations of such multi-hazard effects on buildings and infrastructure in areas along Palu Bay, based on field reconnaissance work, and discusses the main causes of the disaster by focusing upon the combined effects of the cascading geological hazards. To evaluate the tsunami risk potential of the strike-slip event, tsunami simulations for the 2018 Sulawesi earthquake are performed by considering different model settings for spatial earthquake slip distribution, rake angle, astronomical tidal effect, and co-seismic ground deformation. The numerical results indicate that the co-seismic rupture of a moment magnitude 7.5 strike-slip earthquake, having notable dip components can generate damaging tsunami waves at coastal locations of Palu Bay. The conclusion has important implications for future tsunami hazard assessments in active seismic regions where major fault systems cut across a bay or into the sea.

Sentinel optical and SAR data highlights multi-segment faulting during the 2018 Palu-Sulawesi earthquake (Mw 7.5)

“…However, in some circumstances, strike slip earthquake can eventually generate tsunamis 16,17 as for the case of the 28 September 2018 Palu event. On the basis of fault slip modeling, derived from space geodesic data and/or seismic source inversion, numerical simulations have been used to evaluate the possible origins of the tsunami 9,[18][19][20] . Although the early source inversion indicate dominant strike slip, these simulations predict also a non-negligible dip slip component 9,20 likely to make this earthquake more tsunamigenic than initially thought.…”

Good vibrations: living with the motions of our unsettled planet

“…One such event was the 28 September 2018 M w 7.5 Palu, Indonesia, earthquake, which resulted in significant loss of life and property. It was the deadliest earthquake of 2018, and the earthquake and resulting tsunami and mudflows led to the estimated death of more than 4340 people, over 10 000 injuries and the destruction of over 70 000 homes (Goda et al, 2019).…”

“…The ensuing tsunami led to the destruction of the Fukushima Daiichi nuclear power plant and a subsequent moratorium on nuclear energy in Japan amongst other regulatory changes. In the less developed country of Haiti, the 2010 M w 7 earthquake affected over 2 million people, damaged 80 %-90 % of homes near the epicentre and had a death toll of well over 200 000 people (DesRoches et al, 2011;Green and Miles, 2011). The impact of the earthquake in Haiti was likely due to two main causes: unlike Japan, Haiti's economy precludes the necessary level of engineering and disaster preparedness to minimize earthquake damage.…”

“…Yet, if we could not hear the waves as audible sound, they could still provide an impression of our surroundings. Musician Evelyn Glennie, who has a hearing impairment, comments in her Hearing Essay that "hearing is basically a specialized form of touch" (Glennie, 2015). When we could not hear but could only feel the vibration of waves, amplified through a speaker, we were still receiving an impression of the energy coming from the earth.…”

Good Vibrations: Living with the Motions of our Unsettled Planet

“…One such event was the 28 September 2018 magnitude Mw 7.5 Palu, Indonesia earthquake which resulted in significant loss of life and property. It was the deadliest earthquake of 2018, and the earthquake and resulting tsunami and mudflows led to an estimated death of greater than 4340 people, over 10,000 injuries and the destruction of over 70,000 homes (Goda et al, 2019).…”