N. Kósa Judit - Szablyár Péter: Underground Buda - Our Budapest (Budapest, 2002)
"Eppur si muove" - the Seismological Observatory on Sas Hill
since they were first recognised for what they were. Besides increasing our knowledge about the structure of the earth, seismological observation has been a major instrument of verifying compliance with the nuclear test ban since the 1950s. In addition, the assessment of seismological hazards in particular regions has been made urgent by the proliferation of potentially dangerous nuclear and hydroelectrical plants. And such preliminary evaluation necessitated by the considerable additional costs of hazard-reduction depends for its effectiveness on precise observation data. The gathering of seismological data started in Hungary in the wake of the Mór earthquake of 1810. Instrumental observations were not conducted at the time, but the surface area impacted by the quake was fairly well determined in the work of Ádám Tomcsányi and Pál Kitaibel, published in 1814. On 9 November 1881 Hungary was the second country in Europe to initiate an institutional seismological research programme. The first seismograph was switched on in the Royal Hungarian Institute of Meteorology and Terro- magnetography in 1902. Established by Radó Köveslighety and installed in the basement of the National Museum in 1906, the Budapest Seismological Observatory registered tremors for sixty years. Hungary's seismological stations, together with their collected data, were almost completely destroyed in World War II. Only the Kalocsa observatory could resume operations after the war. Subordinated to several institutions, the Seismological Observatory moved into its present home on Sas Hill in 1966. It is now a major department within the Geodesic and Geophysical Institute of the Hungarian Academy of Sciences. The soul of the institute comprises a system of tunnels cut into the dolomite rock of Sas Hill, which is likely to have been made before World War II to serve as an air raid shelter. The tunnels, which were used for the growing of mushrooms in the 1950s, were provided with electric lighting and the instruments sensing the tremors were stood on concrete slabs in the corridors (of semi-circular section measuring three metres across and two metres in height). Originally the gauging instruments were also here (the graphs were scratched into sooty paper by needles); these are now located, together with the researchers' offices, in a building above the surface. The data registered here and elsewhere (there are 18 observatories in 50
