Cultural heritage in landslide-prone and landslide-affected areas

The vulnerability of cultural heritage sites and their susceptibility to deterioration processes are basically correlated to their “ruin” nature and their related conservation history. Furthermore, contribution to their instability and weakening mechanisms can also be derived from the local geohazard factors as well as from the structural relationship with the surrounding geomorphological and geological setting and foundation substratum. Cultural heritage structures and artefacts are often found within natural environments, on which past or recent phenomena and human actions might have produced indirect and direct impacts, in some cases leading to a worsening of the former stability condition. 

The conservation issues can be of particular interest, especially for the management of sites characterized by a high density of heritage concentrated over a relatively wide area. Thus, it might be difficult to ensure a constant and effective ordinary maintenance to prevent structural instability events, especially in times of reduced resources dedicated to preservation activities.

The exploitation of technologies capable of detecting conservation criticalities with a specific field of view, at the same time, covering extended areas of investigation and providing highly detailed information on single elements of interest, certainly represents an effective tool to define sustainable strategies of heritage management.

With this regard, remote-sensing monitoring techniques, are a powerful non-invasive method

for preventive diagnosis of cultural heritage sites, at different scales of analysis, from entire area to single monument. 

In particular, synthetic aperture radar interferometry (InSAR) based on the processing of long stacks of SAR images acquired from spaceborne radar sensors have been successfully exploited for monitoring ground instability for cultural heritage applications. 

Recent works (e.g. Manunta et al 2008, Tapete et al., 2012) demonstrate how the high selectivity of the PSI in distinguishing unstable sectors from stable ones can lead to an updated mapping of deterioration effects on the exposed elements. 

The availability of SAR images since 1992 up to nowadays allow to back-analyse past and recent deformation events, as well as to monitor still active processes in near-real time.

Two distinct spatial scales of analysis can be considered: 

• • Monitoring at ‘entire site scale’, highly indicated for archaeological sites, historic centres, hilltop settlements and, more generally, monumental complexes considered in their entirety, either enclosed or distributed over huge areas, to detect both landslide phenomena active at regional scale and instability localized on single sectors.
• • Monitoring at ‘single monument scale’, focused on group(s) of monuments, even single archaeological structures, whose displacement field can also be assessed in relation to the potential instability of the surrounding geo-morphological setting and foundation substratum.