Within the framework of the Integrated Seismic Survey Oberpfalz 1989 (1SO89) different methods were used to study the seismic structures and properties of the surroundings of the KTB drilling location Oberpfalz /Bavaria. A main target was the determination of those structures which are to be penetrated by the drillhole and will enable direct correlation to the geological and lithological results of the drilling. Therefore, they will play a key role in the interpretation of reflections found in

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... his area and, moreover, provide important clues to deep crustal studies in other regions as well. A number of dominant seismic reflections was detected beneath the KTB by the different seismic methods. However, depth determination is very critical in this spatially inhomogeneous environment since the exact 3D velocity distribution is a pre-requisite for this purpose. Because there is no depth nor velocity control by other deep wells in the study area the velocity distribution can be derived only from surface observations and within narrow limits from seismic observations within the KTB pilot hole. In this paper the structural results obtained from the different seismic studies are compiled and their related depths and the confidence levels are given relying on a most probable 3D velocity distribution which was derived from all seismic information accessible so far.