Two decades after the 2004 Indian Ocean tsunami, coastal settlements in Banda Aceh, Indonesia, have continued to expand, driven by post-disaster urban development dynamics and persistent community preferences to reside near the historic urban core, where economic activities, public services, and educational facilities remain concentrated within tsunami hazard zones. Although post-disaster reconstruction delivered permanent housing and improved building materials, new residential areas have re-emerged within high-risk zones. This pattern raises critical questions regarding spatial compliance, long-term safety, and the extent to which improved structural conditions strengthen coastal resilience. This study examines how post-tsunami settlement expansion contributes to coastal resilience by analyzing spatial growth, settlement typologies, and structural characteristics in the coastal areas of Banda Aceh. The findings indicate that while post-tsunami housing development has improved structural robustness at the building level, continued expansion within tsunami hazard zones has increased overall exposure, constraining resilience at the settlement scale. A Geographic Information Systems (GIS)-based land-use analysis was integrated with structured household surveys to map residential expansion, classify settlement typologies, evaluate structural reliability based on observable attributes such as material permanence and number of storeys, and assess conformity with coastal zoning regulations. The results show continuous residential expansion in hazard areas despite increased reinforced concrete housing that enhances individual building robustness. However, settlement-scale resilience remains constrained because exposure increases faster than structural improvements. Although multi-storey engineered dwellings remain limited, their presence suggests that vertical residential structures with dual evacuation functions could support future risk reduction. The novelty of this study lies in combining spatial expansion metrics with empirical verification of structural reliability as a composite indicator of settlement-scale resilience in a post-disaster context. This study is limited to the Banda Aceh coastal area and does not assess detailed structural capacity beyond observable attributes. Practically, the findings underscore the need for stronger land-use enforcement, adaptive spatial planning, and development controls that differentiate allowable building types in tsunami hazard zones. Socially, policy incentives should prioritize multi-storey engineered permanent buildings over single-storey terrace housing to enable future coastal settlements to function as vertical evacuation options and contribute to long-term risk reduction.
Soviana et al. (Sun,) studied this question.