Area based tsunami risk assessment in West Aceh and Nagan Raya Regencies

Abstract

West Aceh and Nagan Raya Regencies are traversed by the active Great Sumatran Fault, which makes the area vulnerable to geological disasters such as tsunamis. A great Indian Ocean tsunami struck Aceh in 2004. The tsunamis causing injuries, loss of life, and economic downturn as a result of the paralysis of the agricultural sector. Therefore, tsunami disaster mitigation efforts are highly needed in West Aceh and Nagan Raya Regencies. A risk assessment was carried out based on the Regulation of the Head of the National Disaster Management Agency No. 2 of 2012. This study modifies the risk index to provide a more proportional value, employing a simple yet more detailed method than the general method. HEC-RAS 5.0.7 software was used to determine the height of tsunami propagation in the scenario of an 9.1 Mw earthquake, which is based on a previous study. The assessment shows that the area is predominantly at high risk of tsunami. The area based method proved to be more detailed and appropriate than the previous risk index. Disaster mitigation plans are suggested according to both structural and non-structural approaches and are expected to reduce the risk of tsunami-related disasters in West Aceh and Nagan Raya Regencies.