Assessing probability of building damages due to tsunami hazards coupled with characteristics of buildings in Banda Aceh, Indonesia: A way to increase understanding of tsunami risks

Knowing the potential number of buildings that could be damaged by a future tsunami is impor-tant in understanding tsunami risk. There is a limited number of studies that combine the tsunami inundation area that is generated based on probabilistic tsunami hazard analysis and tsunami fragility curves. This study is aimed at providing information on probabilistic tsunami hazard for the city of Banda Aceh (Indonesia), whereby the results could possibly be integrated into tsunami risk reduction in the city. A series of numerical simulations were performed using the Cornell Multi-Grid Coupled Tsunami Model (COMCOT). Tsunami sources were taken from rupture areas generated by a set of earthquakes emanating from the Aceh-Andaman Megathrust segment. Later, tsunami inundation areas that were produced from numerical simulations were used in a proba-bilistic hazard analysis. This research produced three sets of tsunami inundation maps for 250-, 500-, and 1000-year return event periods. Hazard curves were produced based on 230,000 grids. Field surveys were performed in order to assess over 82,000 building units in Banda Aceh, and classified them into six types of buildings, in accordance with HAZUS (Hazards United States). Based on two sets data of buildings in Banda Aceh (measured in 2017 and 2021), there has been an increased number of buildings in the city by around 31%. Most of the new buildings were identified as houses. A set of tsunami fragility curves was used to estimate the damage ratio of each of the buildings. It was found that around 10.5% of the buildings (8708 units of buildings) would likely be totally demolished (swept away), should a 1000-year return period tsunami oc-cur. Inundation maps produced for the 1000-year return period tsunami found in this study por-tray a similar situation to that of the 2004 Indian Ocean tsunami.