Potential impact analysis of the West-Central Java megathrust earthquake in South Cilacap District, Central Java

The region of South Cilacap is known to experience natural disasters in the form of tsunamis. Their geographic location is near seismic gap zones in megathrust areas segmented in West-Central Java. It is predicted that the spit of the West-Central Java segment would lead to a tsunami. This research is conducted to analyze the effects of a megathrust earthquake in the West-Central Java segment in regards to the area of South Cilacap through the model tsunami. This model is based on the shallow water equations in the software COMCOT v1.7. Two scenarios, multi-fault and single-fault, is made with a reference magnitude of 8.7 Mw in which the results show that the arrival time of tsunamis is estimated to take 43 minutes, inundation height ranging from 0,5 – 24 meters, total inundation area ranges from 1128,14 – 1145,4 hectares, and the maximum tsunami height ranges from 11,476 – 13,054 meters. Then, tsunami hazard maps for both scenarios were made based on the inundated areas and compare it with the tsunami hazard maps produced by DLR & GTZ.