Tsunami hazard assessment for the Cilegon industrial zone, Java, Indonesia, by considering various digital elevation model (DEM) datasets and fault source models

Abstract

Sumatra-Java megathrust has been a host of six earthquake-triggered tsunamis in recent decades, which caused severe damage. Cilegon industrial area is a tsunami-prone zone since it is located on the Sunda Strait coast, facing a possibility of large-magnitude earthquake occurrence in the transition zone of Sumatra and Java megathrust. In this study, we assess the tsunami hazard in this area using a deterministic approach from a worst-case earthquake scenario (Mw 8.9). The assessment was done using numerical tsunami modeling, considering various fault source models and digital elevation model (DEM) datasets to accommodate the uncertainty of those factors in the modeling. Two source models (non-uniform and uniform fault slips) and three DEM datasets (global, regional, and local data) were employed. Uniform slip affected the smaller maximum tsunami amplitude than the non-uniform slip, but the travel time from these two source models is similar. Differences in water depth and slope bathymetry profile also strongly influence the tsunami propagation characteristics, particularly in the finest layer model. Generally, the Cilegon coast is consistently hit by up to 9 m of tsunami height from all used scenarios. The estimated tsunami arrival time is more than 60 min, providing enough time for the coastal community to evacuate to the higher ground level. However, the Cilegon industrial area is still categorized as highly hazardous since the tsunami strike can damage industrial buildings, infrastructure, and factory equipment, leading to economic losses.