[1] The Alps are considered as a classical example for an orogen created by continental plate collision. In this study we present new images obtained from deep seismic reflection profiling in the Eastern Alps between Munich and Venice which give rise to examine and revise existing concepts. The seismic sections exhibit a prominent bi-verging reflection pattern at crustal scale. A major ramp-like structure, outcropping at the Inn-Valley fault, can be traced southward over 80 km into the mountain root where relics of the subducted Penninic ocean are expected. New models of the evolution of the Eastern Alps show an upper/lower crustal decoupling along transcrustal thrust faults with opposite thrust directions of both the European and the Adriatic-African continents.

No abstract

This paper was prepared for presentation at the 1999 SPE/IADC Drilling Conference held in Amsterdam, Holland, 9-11 March 1999.

Drill‐bit noise and RVSPs. Time and depth migration of seismic data usually is based on velocities estimated from surface measurements. The actual velocities, which calibrate the depth‐migrated seismic to the well data, are determined after the well is drilled using check shots and VSPs. By then, it may be too late to correct for seismic migration velocity imprecision and impact the well’s success. The earlier we can obtain such velocity information, the more time will be available for reprocessing (remigration of either the seismic or any depth maps), if necessary. It is therefore very useful to determine the velocities to calibrate seismic and well velocities while drilling. This allows us to better locate the drill bit in time on the seismic section; to redirect the well, if necessary; and to gather as much further information as possible on the rocks ahead of the bit.

The Alps—the youngest and most elevated mountain range in Europe—have inspired ideas about orogenic evolution for a long time. During the late 1980s, the western Alps were the site of intensive research using seismic profiling methods by Swiss, Italian, and French national programs [Rome et al., 1990; Pfiffner et al., 1997] .These investigations, some of which formed part of the European Traverse [Blundell et al., 1992], provided a great wealth of new data relevant to the Alpine orogeny. This orogeny is generally viewed in the context of the collision of the European and the Adriatic/African continental plates after the closure and subduction of the Penninic Ocean since about 40–50 Ma.