In autumn of 1997 two borehole tiltmeters, type AppliedGeomechanics, A722 were installed for monitoring recentmovements of the Mecsekalja fault in Southwest Hungary. Beside the continuous tilt measurements a geodetic network for GPS and electronic distance measurements (EDM) and a levelling line crossing the fault were established. The borehole tiltmeters are continuously recording and the geodetic measurements (GPS, EDM, precision levelling) are repeated twice in a year, in spring and in autumn. This paper presents experiences and results of the tiltmeter measurements and analyses the disturbing effects e.g. earth tide, tilt caused by ground water level variations, precipitation of the surrounding vegetation, etc. superposed to the tilt signal. The paper shows some of these effects which can use to prove the goodness of the coupling between the instrument and the ground.
The investigation of the coupling between building and ground motions is of great importance because the results contribute to the planning of stable, motionproof constructions and to forecast of damages. For monitoring ground and building motions the TV tower in Sopron, Hungary was chosen. Two borehole tiltmeters, Applied Geomechanics Inc., model 722A were used for continuous and short-term high frequency tilt measurements. One of the instruments was installed on the concrete basement of the TV tower and the other in a borehole drilled at a distance of about 90 m beside the tower. This paper presents continuous data series of a length of more than one year, high frequency tilt measurements with sampling rates of up to 10 Hz and discusses the first experiences of the observations.