Fragility based characterization of alternative tsunami evacuation buildings in Banda Aceh, Indonesia

Abstract

Providing sufficient structures suitable for vertical evacuation from tsunamis is critically important for a tsunami-prone city like Banda Aceh, the city most severely affected by the 2004 Indian Ocean tsunami. However, lack of sufficient financial capacity along with difficulties to find affordable land to be acquired have prevented some tsunami-prone cities to do so. This research is aimed at investigating potential structures to serve as alternative tsunami vertical evacuation buildings. The research was performed by mapping modified Building Tsunami Vulnerability (BTV) based on numerical simulations and types of the buildings. In 2018, all 79,420 structures in Banda Aceh were surveyed and classified into five building categories. Numerical simulations were performed using the Cornell Multi Grid Coupled Tsunami Model (COMCOT). Five scenarios of earthquake-triggered tsunamis were incorporated in the simulations, namely magnitude 9.2 Mw, 9.0 Mw, 8.8 Mw, 8.6 Mw, and 8.4 Mw events. Results of this research revealed that some 96 to 134 buildings could be used as alternative tsunami vertical evacuation buildings. None of the surveyed buildings could be classified as very low BTV condition. The buildings were schools, hotels, an assembly hall, government offices, and houses. The capacity of the alternatives evacuation buildings to accommodate tsunami evacuees were later calculated. The alternative tsunami evacuation buildings are expected to facilitate about 4 times the present capacity of six official tsunami escape buildings in Banda Aceh, Indonesia.