Santorini Island, located in the Southern Aegean Sea, is prone to tsunamis due to its proximity to the Hellenic subduction zone, which is one of the major tsunamigenic areas. Characteristic events, such as those of 365 A.D. and 1303 A.D. greatly affected the coasts of the Eastern Mediterranean Sea, causing significant loss of life and construction damage. Tsunami disaster risk is nowadays significantly higher due to the increased exposure of the buildings as a result of the economic and touristic growth of the Aegean Islands. This study focuses on the eastern coast of Santorini, since its morphology and human presence amplify the necessity to assess its building vulnerability. After conducting an exposure analysis at the settlements of the eastern coast, Kamari poses the highest physical, social and economic relative exposure to any potential natural hazard. The main objective of this research is to quantify the building stock’s vulnerability to tsunami hazard. For this purpose, a “worst-case run-up scenario” was developed. Considering the history of tsunamis in the Aegean Sea, an extreme sea-level rise after a 10 m a.s.l. tsunami run-up, caused by an earthquake with M_w~8.5, was assumed. The relative vulnerability of the buildings in Kamari was calculated via the application of the Papathoma Tsunami Vulnerability Assessment (PTVA-4) analytic model. The results indicate that 423 buildings are within the inundation zone, 58% of which are characterized as highly and very highly vulnerable to tsunamis, revealing the problematic characteristics of the building stock, offering important information to the decision-makers to mitigate a possible future tsunami impact.

In the early months of 2025, a significant seismic activity was recorded in the area between Santorini and Amorgos, raising concerns about the potential occurrence of a major earthquake and a possible tsunami. The objective of this study is to assess the earthquake-triggered tsunami hazard in the Santorini-Amorgos Tectonic Zone (SATZ) by simulating tsunami processes using the MOST (Method of Splitting Tsunami) numerical model, implemented through the ComMIT (Community Model Interface for Tsunamis). High-resolution bathymetry and topography were employed to model tsunami generation, propagation, and onshore inundation. A total of 60 simulations were conducted using a deterministic approach based on worst-case scenarios. The analysis considered six major active faults with two kinematic types, pure normal and oblique-slip, and assessed tsunami impact on five selected coastal study areas. The simulations results showed potential maximum run-up values of 4.1 m in Gialos (Ios), 2.7 m in Kamari (Santorini), 2.4 m in Perissa (Santorini), 1.5 m in Katapola (Amorgos), and 2.3 m in Chora (Astypalaea), in some cases affecting residential zones. Inundation flows also impacted the main ports of Gialos, Katapola, and Chora, highlighting the exposure of critical infrastructure. Although earthquake-triggered tsunamis represent a potential hazard in the SATZ, the results indicated that it is unlikely to cause a widespread disaster in the study areas.