ELASTIC PARAMETERS OF WEST BOHEMIAN GRANITES UNDER HYDROSTATIC-PRESSURE

The West Bohemian seismoactive region is situated near the contact of the Moldanubian, Bohemian and Saxothuringian units in which a large vo lume is occupied by granitoid massifs. The spatial distribution of P-w ave velocities and the rock fabric of five representative samples from these massifs were studied. The P-wave velocities were measured on sp herical samples in 132 independent directions under hydrostatic pressu re up to 400 MPa, using the pulse-transmission method. The pressure of 400 MPa corresponds to a depth of about 15 km in the area under study . The changes of P-wave velocity were correlated with the preferred or ientations of the main rock fabric elements, i.e., rock forming minera ls and microcracks. The values of the P-wave velocity from laboratory measurements on granite samples fit the velocity model used by seismol ogists in the West Bohemian seismoactive region.