Three-dimensional seismic modelling of the crustal structure between East European Craton and the Carpathians in SE Poland based on CELEBRATION 2000 data

Abstract

SUMMARY In this paper, we present results of 3-D first-arrival tomography applied to data recorded in SE Poland during the CELEBRATION 2000 seismic experiment. The target area covers ca. 500 × 500 km 2 and represents a complex geological setting from old Precambrian platform (East European Craton, EEC), through the crustal blocks (terranes) that form the TransEuropean Suture Zone (TESZ) to the young Alpine orogen—the Carpathians. Contrasting velocity distributions in various geological units makes the tomographic inversion challenging. For this reason, much attention was paid to the inversion methodology. We tested ‘multioffset’ and ‘multiscale’ approaches. By increasing the offset range in the ‘multioffset’ inversion we have independently constrained different depth ranges of our model. We have found that the ‘multiscale’ method, that is, the gradual stepping from bigger to smaller model cells produced the preferred solution. Resolution of the resultant crustal model was determined by performing checkerboard and restoration resolution tests. Lateral resolution of the order of 25 km is inferred down to 10 km depth and 50 km down to 25‐30 km depth. We have also applied a quasi-Monte Carlo analysis to determine the absolute errors of model parameters, which to our knowledge, is the first such attempt in case of a 3-D wide-angle data set. The mean uncertainties of our tomographic velocities are 0.1 km s −1 , but some anomalies are recovered with