Tsunami Risk in Pacitan, Indonesia: Spatial Patterns of Building Vulnerability in an Emerging Coastal Tourism Destination

Coastal tourism destinations along the southern coast of Java face significant exposure to tsunami hazards. This study models potential coastal inundation using the official deterministic worst-case scenario of an 11 m tsunami wave and evaluates tsunami-related building vulnerability in Watukarung, Indonesia, through the Papathoma Tsunami Vulnerability Assessment framework (PTVA-4). The analysis incorporates structural characteristics, water-related exposure, surrounding environmental conditions, and a composite Relative Vulnerability Index (RVI), based on field surveys of existing buildings within the inundation zone. The field survey identified a largely uniform stock of low-rise, non-engineered structures lacking substantial natural or engineered protection. Most buildings fell into moderate to high structural vulnerability (SV) categories, with concentrations of high and very high vulnerability along the Watukarung Beach corridor and near the fish landing site . Inundation modelling reveals that the greatest water depths occur along the immediate coastal strip and low-lying areas near the river mouth. Consequently, water inundation vulnerability (WV) was mostly high, with only a small proportion of buildings in the average and minor vulnerability classes. RVI results indicate that 33.34% of buildings are classified as high or very high vulnerability, while 24.36% are considered average, with higher vulnerability concentrated in coastal tourism zones. These patterns are closely linked to the prevalence of single-storey masonry buildings, shallow or non-engineered foundations, and limited natural barriers. The results demonstrate that tsunami risk in Watukarung is shaped not only by hazard intensity but also by the interaction of building characteristics and tourism land use. This spatial convergence of hazard, vulnerability, and tourism exposure emphasizes the requirement for risk-informed coastal planning and improved tourist safety management in tsunami-prone areas.