Monitoring Landslide Risk: Application To Urban Planning In Santorini

Urban planning utilises land area and minimises environmental impact of a city. Urban planning is particularly important for cities that has limited land usage such as Santorini (Greece). Historical buildings and unique architecture of Fira and Oia that are built upon the caldera cliffs prove to be famous among the tourists after seeing a rapid growth of the tourism industry in the past few decades.

As a result, construction activity escalated and the need for land use planning to expand urban development is more than necessary. This eventually increase the risk of anthropogenic-induced landslide due to the increased stress load on the caldera wall. In this study, we monitor the ground subsidence at the historic municipality of Fira and Oia caused by urbanisation using remote sensing techniques, the risk of a landslide by assessing the geological and geotechnical features of the caldera wall, and present an off-limit construction hazard map to the city council to guide them in future urban planning while reducing the risk of anthropogenic-induced landslide. Justification of resources required:Two days of preliminary survey in Fira and Oia, Santorini to locate prospective sites for the installation of Global Positioning System (GPS) equipment’s, collect stratigraphic log and noting scree slopes forming below buildings. 8 GPS equipment will be needed for this project. The sensitivity of the GPS equipment required for this study is in centimetre scale to ensure accurate data. GPS with millimetre sensitivity is not chosen because it may pick up noise introduced by human activity. When choosing a site for GPS installation, factors to consider includes: maximum direct sunlight for maximum efficiency of the solar powered GPS equipment, accessibility to GPS site for personnel monitoring it and buildings on cliffs particularly with scree slopes below it. After the preliminary survey, one field season is needed to:

• Conduct a detailed study of the vertical profile in the 8 proposed GPS installation site and
• install GPS sites to collect ground subsidence data across the two cities. An estimated 8 days would be needed to conduct logging exercises and install GPS on site. The trip is suggested to take place in the winter so that the GPS data collection could begin with a less noisy data when there are less tourists. Before installing GPS, a permission is needed from the government and city council to conduct scientific research in the area and a permission from each of the site’s landlord to occupy their space. To make sure data could be uploaded to the database in real-time, a wireless network would be required. Personnel from a local university is also required to monitor the GPS and update their firmware periodically. Data access to existing GPS monitoring sites from other universities is also required to have a better resolution through the network and a better collaboration in this project.

While some data from space agencies are freely available thanks to its open data policy, a full access of Synthetic Aperture Radar (SAR) data from all space agencies with satellites collecting swaths above Santorini could be beneficial to reduce uncertainties from different tracks and line-of-sights. Furthermore, access to supercomputer with multiple graphical processing units and runs parallel computing is required to process the huge datasets and images from the satellite. An unconfined compressive test (UCT) machine from the engineering department would be needed to test the structural integrity of the cliff based on the stratigraphic log.