Quaternary fault activity in the SW Pannonian Basin: GPR surveying in Bilogora (NE Croatia)

Abstract

In areas experiencing low deformation rates, landscapes provide limited evidence of ongoing tectonic activity, being either masked or altered by exogenic processes. Accordingly, the identification of fault activity and near surface deformation is commonly accomplished by multidisciplinary research combining geological, geophysical and geomorphic methods. In this study, Quaternary fault activity in the SW Pannonian Basin is investigated in the region of Bilogora, NE Croatia. The study area is positioned along the SW margin of the Drava Depression that was uplifted during the Pliocene and Quaternary within the Drava Depression Boundary Fault Zone. In this fault zone six GPR profiles were recorded. Reflection patterns, radar facies and truncations determined fault activity and near-surface deformation at four locations with vertical displacements of ≤1 m. At two sites, profiles did not show truncation of the shallowest reflections, however, an elevation difference of ca. 10 m between two palaeostream channels along one of the profiles suggests Quaternary uplift accommodated by a mapped fault. Considering the importance of the seismogenic potential of active faults and their correlation with the seismicity of Bilogora, this research will be followed by additional studies of near-surface strata deformation and palaeoseismological fault properties.