Multiscale Analysis of Geo-Hazards Affecting the Alhambra Cultural Heritage

Abstract

This paper presents a multiscale methodology to perform successful geo-hazards assessment in the context of Cultural Heritage. The methodology, defined in the European PROTHEGO project, has been applied to the Alhambra case study. Alhambra is an important Word Heritage site located in Andalusia, Spain. The site is prone to suffer flood, earthquake and landslide phenomena. The proposed multiscale methodology leans on new remote monitoring and modelling technics that not entail aesthetic and functional impacts on the site. For large-scale monitoring, satellite remote sensing technology enables to detect and characterize spatiotemporal ground and structure deformation as a whole, with up to millimeter precision. For very local phenomena analysis, small-scale monitoring based on Terrestrial Laser Scanner and airborne drone digital photogrammetry surveys enables to detect erosion processes that affect the slopes of the citadel. Furthermore, numerical modelling enables geo-mechanical instabilities to be quantified at different scales. Large-scale modelling shows that the most dangerous slope is located at the San Pedro cliff site. Small-scale stability analysis in the San Pedro cliff shows that a slope failure, triggered by a possible earthquake scenario, could reach the wall foundations of the Alhambra citadel located 22 m behind it. Finally, very detailed small-scale modelling, using very precise digital elevation models, enables to track local instabilities and erosion phenomena. Such a multiscale, interdisciplinary approach is the most effective way to identify, assess and monitor risks, strengthening disaster preparedness at heritage property.