Towards multi-hazard earthquake-flood impact assessment on ancient monuments based on UAVs, photogrammetry and high-fidelity computational models

Cultural heritage monuments are invaluable assets that embody the history, culture, and identity of civilizations, making their preservation a global priority. Understanding the multi-hazard risks they face, and particularly earthquakes and floods, is essential to developing effective strategies for their protection in seismic regions and ensuring their resilience for future generations.

This study presents a comprehensive multi-hazard assessment of a significant archaeological site in Greece: the Temple of Apollo at Aegina (Kolona), which was conducted as part of a the Horizon Europe project TRIQUETRA. Detailed and accurate geometric documentation of the archaeological site was done, using UAV imagery (DJI Mavic 3 Enterprise) and GNSS measurements of ground control points, acquiring more nearly 6000 images. Using multi-image photogrammetric techniques a 3D texture model of the site and monuments, with an RMS error of 4 cm, a digital surface model with a resolution of 1 cm and a high-resolution orthophoto with a pixel size of 1 cm (groudel) were produced.

Based on these digital replicas, advanced three-dimensional Finite Element (FEA) models were developed using solid elements to evaluate the structural response and vulnerability of these heritage structures under single hazards and combined earthquake and flood scenarios. The methodology integrates site-specific geotechnical data, historical structural modifications, and current preservation states to create realistic simulation models. The numerical analysis incorporates both seismic loading conditions based on regional hazard data and flood impact forces derived from hydraulic assessment. The multi-hazard approach considers various combinations of seismic and flood events, providing insights into potential failure mechanisms and structural vulnerabilities. Results highlight critical areas requiring preservation attention and demonstrate the varying resilience levels of different structural components under combined loading conditions.

This research contributes to the field of heritage structure preservation by establishing a novel framework for multi-hazard assessment of archaeological sites. The findings provide valuable insights for developing targeted conservation strategies and disaster risk reduction plans for these irreplaceable cultural heritage sites.

Acknowledgments: This work is based on procedures and tasks implemented within the project “Toolbox for assessing and mitigating Climate Change risks and natural hazards threatening cultural heritage—TRIQUETRA”, which is a Project funded by the EU HE research and innovation program under GA No. 101094818.