[M-IS07] [EE] Conservation of natural geosites and cultural heritages: weathering process and damage assessment

[MIS07-05] Historic porous limestone quarries in the city of Budapest (Central Europe), their exploitation history and preservation

*Akos Torok¹ (1.Department of Engineering Geology and Geotechnics Budapest University of Technology and Economics, Hungary, ([e-mail]))

Keywords:limestone, cultural heritage, urban development, subsurface galleries, cellars

Budapest, the capital of Hungary (Central Europe) had a rapid urbanization and transformation at the end of 19^th and at the beginning of 20^th century. The population of the city grew from 300,000 (in 1880) to nearly 900,000 (in 1920). This process invoked an urgent and continuously growing need of construction material. The closest resource that was available was a porous limestone. The Miocene limestone has appropriate properties for constructional use. It has a high porosity (up to 40%), a low unit weight (light stone) and good workability (easy to cut and carve). Due to the appropriate properties its use already began by the Romans (1^st and 2^nd century AD) and continued in the medieval period, however major and large-scale exploitation was mostly in the late 18^th to early 19^th century associated with the population boom. The porous limestone covered smaller elevated hills on both side of river Danube in Buda and in Pest site. The exploitation of the stone first started in open quarries. The first quarries were located outside of the town during the Roman times. The Medieval stone exploitation was also from external quarries, while from the 18^th century onward with the city development the suburbs provided stone materials: The stone was used for the construction of public buildings and housing. These monuments, which date back to that period, are now in the city centre (House of Parliament, Opera House, Mathias Church), but at the construction time some of them were in the suburbs (e.g. Central Building of Technical University). The first quarrying operation started where vineyards and orchards were located. Due to the increasing need of stone larger areas were used for quarrying and it caused a conflict with agriculture, and caused the significant loss of fertile areas. Consequently, in the second phase of stone exploitation the quarrying activity were shifted toward subsurface galleries. It reduced the land use and resulted in the excavation of long passages and larger galleries at subsurface. In the late early 20^th century the operation of the quarries terminated and galleries became abandoned. These abandoned quarries than were used as wine cellars or occupied by inhabitants and became a dwelling and housing place, an urban habitat. In the 1960’ies the population were pulled out from these unhealthy “cave dwellings” and some of the galleries were used as storage facilities and mushroom cultivation sites. At present these subsurface openings cause high risk of land development (collapse) and limit the land use of the given area. Despite their engineering geological risks the galleries and previous quarries represent historic values and their preservation is crucial. The protection of these galleries and subsurface quarries are now in progress. Coevally with the preservation measures it is necessary to record the condition and preserved values (quarrying activity related tool traces, inscriptions, etc.) of these systems. It is also crucial to make surveys and stability calculations to avoid outbreaks and collapses. This paper points out that urban development, cultural and geological heritage needs to be understood and managed in a sustainable way.