Determination of Authentic Formulae for Seismic Acceleration Decay in the Bohemian Massif

Two seismic profiles were established for experimental determination of a decrease of the maximum ground motion acceleration amplitudes as a function of the distance and magnitude of seismic sources. Profile I (direction N-S) was equipped by four accelerometers in the period from 2003 July 1 till 2004 December 31. At present, five additional seismometers are dislocated along the Profile II (NW-SE). In this paper, only mining tremors from Legnica-Głogów rockbursts region recorded on Profile I were processed. The local seismic service of Lubin mine yielded data about geographic and time coordinates of foci, as well as local magnitude ML. Magnitude values ML were correlated with magnitude values MV given in the bulletins of near seismic events, recorded by the Czech regional seismic network. Preliminary acceleration attenuation relation was derived for Profile I in the Bohemian massif. Input magnitude ML data are in the interval 2.7-4.1 and epicentre distances are 100-250 km. The obtained relation was compared with two relations derived for data abroad.