History and Function
The Seismological Service was established at the Zentralanstalt für Meteorologie und Geodynamik (ZAMG) in 1904, Victor Conrad (1876-1962) was appointed as the first head. Conrad developed a pendulum, which was named after him, for measuring stronger ground movements. He became Professor of Cosmic Physics at the Franz Joseph University in Czernowitz, crown land Bukovina, in 1910. From 1919 to 1934 he again served as the head of the Seismological Service at ZAMG. In the paper “Laufzeitkurven des Tauernbebens vom 28. November 1923” (Travel-time curves of the Tauern earthquake of November 28, 1923) Conrad described the nature of the P-wave, which is the primary wave with a high velocity and therefore the first wave recorded by a seismograph, leading him to suggest that the Earth’s crust consists of two layers. The separation of these layers became known worldwide as the “Conrad discontinuity.”
Conrad emigrated with his wife Ida to the USA in 1939, here he focused on climatological research. He taught inter alia at Harvard University in Cambridge, Mass. untiringly until the age of 80. Ida Conrad, who passed away in 1969, conferred in her will a legacy to the ZAMG, with the wish that „… from the estate a building will be erected, serving geophysical and meteorological research, and will be named after Victor Conrad.”
The generous legacy of Ida Conrad and subsidies from the Province of Lower Austria made it possible to set up the Conrad Observatory at an excellent location. This external financial support was the starting point for the implementation of this ambitious project by the Ministry of Science and Research (today BMBWF, Ministry of Education, Science and Research).
In 1975 Peter Melichar was commissioned by the ZAMG to find a suitable site for a new geophysical observatory. The order included the design and structuring of the observatory to meet the specific needs for a research centre for seismology, gravimetry and geomagnetism. In 1978/79 a suitable site was detected on the Trafelberg in 1,100 meters above sea level. The essential criteria for the location are defined by: free from interference by natural and artificial sources such as vibrations and influences of technical equipment and machinery, which generate electromagnetic fields. In addition, the location requires a geological underground, containing spacious largely non-magnetic rocks.
Indeed, the Trafelberg has all these features and it is now a forest conservation area with direct road access, but without any settlement activity.HR Dipl. Ing. Peter Melichar
To be independent from seasonal fluctuations an underground construction as design variant was chosen, which makes the observatory – a geophysical laboratory – independent of weather conditions. In the tunnel system, the temperature of + 7° Celsius remains constant. This is a real gift the mountain offers and it brings ideal conditions for highly sensitive sensors and electronics – leading to a most significant thermal low noise reduction.
The Conrad Observatory, with its two separated underground sections SGO / seismo-gravimetric observatory and GMO / geomagnetic observatory, has a total tunnel length of 1,166 m with 8 up to 200-meter deep boreholes accessible from the tunnel floor.
The entire GMO tunnel system, more then one kilometre, was built by the Austrian company ÖSTU STETTIN in a special nonmagnetic modification of the new Austrian tunnel construction technique. White cement and lime, fiberglass anchors, fiberglass grids and mats were the materials used. The central heart of the GMO is the 3D gradiometer magnetometer system from GEM Systems. In its configuration, it is currently the world's most sensitive measurement system of its kind. It includes two horizontal gradiometers in north-south and east-west directions as well as a vertical gradiometer. The maximum extension on the three axes x, y and z is 200 meters each. In addition, a variable gradiometer system was integrated for smaller distances between 5 and 50 m. Measurements in the Femto Tesla range are now carried out with 9 potassium sensors. Everyone knows that earthquakes can not (yet) reliably predicted, but it is known that due to the pressure build-up in the earth’s crust just shortly before an earthquake happens very small electromagnetic signals are generated in the rock masses. This leads to induction and piezoelectric effects, which then cause extremely small changes in the current systems of the ionosphere. Due to the extreme resolution of the 3D gradiometer on the GMO up to the Femto Tesla range, these magnetic precursor effects may be recorded and analysed for the first time. This, in combination with the seismic measurements at the Conrad Observatory, offers a potential opportunity for the development of new and more reliable earthquake prediction models.
The first building phase of the Conrad Observatory, the SGO started on 13 July, 1998. The opening ceremony took place on 23 May, 2002. It is used for research and development in seismology and gravimetry, as well as for applied sciences. The ground-breaking ceremony for the second phase, the GMO was 15 September, 2008. After the official opening on 21 May, 2014 the GMO became an active centre for geomagnetic research and development as well as geomagnetic standard measurements. In various projects, geophysical and electromagnetic phenomena are carried out in national and international projects.
From the beginning, the goal was to establish the Conrad Observatory as an international research centre and meeting place for the science community.
Text: Christa Hammerl und Peter Melichar