Geophysical Aspects of Recent Deep Seismic Soundings of the German Crust

Refraction and (near-vertical as well as wide-angle) seismic reflection investigations of the deep crust have a long tradition in Germany. Many advances were made during the last two decades in developing the seismic methods to provide adequate tools for imaging the crust and extracting the relevant subsurface parameters. Within the framework of the International Lithosphere Program, seismic investigations were extensively performed by DEKORP (Deutsches Kontinentales Reflexionsseismisches Programm ≡ continental seismic reflection program) and XTB (Kontinentales Tiefbohrprogramm ≡ continental deep drilling program). These gave increasingly preference to the near-vertical reflection method as a tool to image the crust with the highest possible resolution. The obtained seismic measurements were very valuable to decide upon one of the two potential drilling sites for a deep well (approx. 12–15 km) in the Hercynian basement complex. From the two initial sites — the Oberpfalz location in north-eastern Bavaria and the Black Forest location in southwestern Germany — the first one was finally chosen.This paper aims at summarizing (a)results and progresses made with the deep seismic sounding — in particular the near-vertical — methods before and during the KTB and DEKORP surveys(b)ideas and concepts, on how further seismic surveys in the immediate neighbourhood of the chosen drilling site should be performed in order to predict and investigate the geological environment of the scheduled deep well.