Description: The c. 93 km long profile 1A was recorded in 1987 as part of the joint seismic reflection venture DEKORP 1 of the DEKORP (German Deep Seismic Reflection Program) and BELCORP (Belgian Continental Reflection Seismic Program) project steering groups. It was surveyed to investigate the deep crustal structure of the western Rhenish Massif with high-fold near-vertical incidence vibroseis acquisition. The objectives of the experiment were to analyse deep Variscan and post-Variscan crustal structures in the region and to compare them with the results from the eastern Rhenish Massif gathered from the survey DEKORP 2N. The first results were presented by DEKORP Research Group (1990, 1991) and supplemented by many other researches. The Technical Report of line 1A gives detailed information about acquisition and processing parameters. The European Variscides, extending from the French Central Massif to the East European Platform, originated during the collision between Gondwana and Baltica in the Late Palaeozoic. Due to involvement of various crustal blocks in the orogenesis, the mountain belt is subdivided into distinct zones. The external fold-and-thrust belts of the Rhenohercynian and Saxothuringian as well as the predominantly crystalline body of the Moldanubian dominate the central European segment of the Variscides. Polyphase tectonic deformation, magmatism and metamorphic processes led to a complex interlinking between the units. The Rhenohercynian Zone is a foreland fold-and-thrust belt cropping out in the Rhenish Massif which extends from the Ardennes to the Harz Mountains. This geological unit consists predominantly of Devonian and Lower Carboniferous rocks affected by very low-grade metamorphism (DEKORP Research Group, 1991). The nearly NW-SE running survey 1A starts at the Dutch-Belgian border southeast of Maastricht on the southern flank of the London-Brabant Massif. The seismic line also crosses the northern rim of the Rhenish Massif passing through the Aachen Thrust, a part of the North Variscan Deformation Front. 1A runs over the Stavelot-Venn Anticline into the Northern Eifel intersecting the N-S trending axial depression of the Eifel North-South Zone nearly perpendicularly to its strike direction. The eastern flank of the depression was affected by volcanic activity of the High Eifel Volcanic Field during Early Tertiary times (DEKORP Research Group, 1991). Near Adenau the southern end of line 1A crosses the northern beginning of line DEKORP 1B, which proceeds through the Kelberg Magnetic High farther to the south.