SEISMIC WAVES VELOCITIES INFERRED FROM THE SURFACE WAVES DISPERSION IN THE MALE KARPATY MOUNTAINS, SLOVAKIA

摘要

The study area of Western Carpathians belongs to one of the most seismically active regions in Slovakia, where the available velocity models are not precise enough for accurate location and determination of focal mechanism. To improve the uppermost part of the currently used models, seismic surface wave data from two blasts in the quarry Rohoznik, recorded at the MKnet local seismic network, were analyzed. Group velocity dispersion curves of Rayleigh and Love waves were determined by the frequency-time analysis. A mean group velocity dispersion curve for Love and Rayleigh waves for the central part of the MKnet network was settled and consequently joint inversion, for the period range 0.9 - 2.7 s, was performed to obtain a 1-D velocity model using the isometric method. The 11-layered model extends to depth of 2.5 km and indicate increase of the velocities from the surface down to the depths of 0.9 km. Then, velocities slightly decrease. The minimum of the low-velocity zone is at the depth of 1.8 km after which the velocities moderately increase to the velocity of the halfspace with v(P) = 5.35 km/s and v(S) = 2.96 km/s.