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Αν Ζαχαράκη 07 11 2020 (133) copy edit.j


Under The Landscape



Boulouki conducted interdisciplinary research, focusing on the deserted settlement of Agrilia as the case study for investigating the use of the local volcanic materials in the vernacular architecture of Therasia and Thera. The objective of this research was the partial retrieval of the forgotten craftsmanship underlying the cave structures of Santorini Archipelago and the design of compatible and optimised materials which was applied in selected locations of Agrilia settlement. The results of the research was also tested within an artistic experimentation in sculptural creations.

The volcanic tephra the locals call 'aspa' or the famous 'theran earth', as recorded in the history of materials technology, was mined in Thera-Therasia from early 19th to mid-20th century. Theran earth constituted an important mineral in the early Greek State’s industrial  history; it was used as building material, especially in major marine and land construction projects like harbors and piers in Greece and abroad, due to its so-called hydraulic properties.


In the traditional architecture of Santorini Archipelago, local craftsmen used the 'theran tephra' mostly as collected in situ from the excavation debris during a cave dwelling construction. It constituted the primary component in the diverse building materials employed in the underground settlements network that was developed in the area throughout the history. 

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Deciphering the local building materials based on the use of theran tephra and lime entails the laboratory examination of a series of samples from Agrilia settlement. The aim was to unveil their physicochemical and mechanical properties, as well as their production technology and application process. In situ survey of the cave settlement of Agrilia, bibliographic research as well as interviews with local masons frame the scientific worked as valuable sources for the documentation of traditional materials and techniques. 


The field of study regards some of the most representative techniques of Therasia:

  1. The binding mortars used for the stones’ assemblage in the cave structures.

  2. The plastering techniques with emphasis on the special waterproofing coatings used in flooring systems and water cisterns

  3. The pumice aggregate concretes, very similar to Roman Concrete technique, used to create the cast vaults of the cave dwellings and occasionally building units like bricks.



A collaboration with the Building Materials Lab of NTUA and Lithos Laboratory of the Hellenic Survey of Geological and Mineral Exploration (HSGME) was established by Boulouki, for the conduction of the analyses and interpretation of the results. Furthermore, the local materials’ investigation was approached through the perspective of artistic expression. Students from the Athens School of Fine Arts (ASFA) created original sculptural works based on the traditional materials and upon the research findings.

Throughout the research, scientific support and guidance was provided by the international expert Marie D. Jackson, Associate Professor of the Department of Geology and Geophysics from the University of Utah, as an expert on volcanic materials and their use in mortars and concretes throughout the history of architecture.


Petrographic image from a “theran earth” sample, H.S.G.M.E. Dr. Christos Papatrechas



The understanding of the historic materials and local techniques, as well as the design of compatible restoration syntheses created the methodological toolset for an approach that complies with the modern principles of cultural heritage preservation. This is an approach which is appropriate for the documentation of a knowledge mostly forgotten, yet important for the history of  architecture and of the area. 


A modern restoration project that fosters the use of traditional techniques and engages local masons contributes towards the appreciation and rejuvenation of this knowledge while broaching how the historical knowhow may be integrated into restoration practices which are more consistent with the cultural and historical context of a place.


The interdisciplinary collaborations within this project are an in depth exploration of theran earth’s ‘character’; from its physicochemical characteristics and mechanical strength to its ability to be part of artistic expression and cultural values.

Handbook for the traditional building techniques of Therasia and Santorini.

Based on the experience and knowledge gained from the research and the participatory restoration project in the underground settlement of Agrilia, an openly available handbook was created, for the dry stone structures of Therasia and Santorini and the use of building materials made of lime and the local volcanic tephral,  theran earth.


The handbook was developed in the framework of the project "Under the Landscape: Participatory interventions for the protection and promotion of the man-made and natural environment of Therasma", as part of the programme "Innovative actions with citizens" , founded by the Green Fund".

View and Download the Handbook (in greek) here:

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