Geophysical Institute of the ASCR

was designed to continue previous experiments Polonaise’97 and CELEBRATION 2000 (Guterch et
al. 1999, 2003) and it was prepared in the same geometry. Scientific organizations involved were led
by the experiment teams from geophysical and geological communities in the Czech Republic,
Poland, Austria, the USA, Canada, the Slovak Republic, Hungary, Denmark and Finland. In the Czech
Republic, experts from the Geophysical Institute of the ASCR, Institute of Rock Structure and
Mechanics of the ASCR, and Institute of the Physics of the Earth MUNI Brno participated in the
project.
The layout of each experiment was a network of interlocking recording profiles (Fig. 17). Shots were
fired along each profile with the average distance of 30 km, data were sampled at intervals of 10 ms
and were recorded mainly by one-component stations TEXANs with station spacing 3 km. For more
details about SLICE project refer to Brož et al. 2005.
Interpretation of a large set of refraction and wide-angle reflection data involved three different
approaches: (i) tomographic inversion of the first arrivals of P waves; (ii) parametric kinematic
inversion of travel times of Pg, Pn and PmP waves; (iii) trial-and-error forward modelling of the entire
wave field with SEIS83 program package (Hrubcová et al., 2005). The results of these three methods
gave 2-D velocity models down to the depth of 40-50 km with P-wave velocities ranging around
3.5 km/s in sedimetary basins to 8.5 km/s for the uppermost mantle parts (Fig. 18). Relative velocity
errors were in range of 5% depending on ray coverage, the uncertainties in the Moho depth
determinations were less than ± 2.5 km. The differentiation of the wave field, velocity models and the
depth of Moho in different areas enabled to determine three types of crust-mantle transition in the
Bohemian Massif reflecting variable crustal thickness and delimiting contacts of tectonic units in
depth. These models are consistent with hypothesis of laminated Moho, sharp or gradual velocity
transition at Moho depth or indications of low velocity anomalies in lower crust.
Fig. 18. Comparison of two depth-velocity cross-sections.
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