HR: 0830h
AN: S21F-0397    [PDF]
TI: A 3-D seismic model of the Eastern Alps derived from CELEBRATION 2000 and ALP 2002 data
AU: * Behm, M
EM: mbehm@luna.tuwien.ac.at
AF: Institute of Geodesy and Geophysics, Vienna University of Technology, Gusshausstrasse 27-29, Vienna, A-1040 Austria
AU: Brueckl, E
EM: ebrueckl@luna.tuwien.ac.at
AF: Institute of Geodesy and Geophysics, Vienna University of Technology, Gusshausstrasse 27-29, Vienna, A-1040 Austria
AU: Chwatal, W
EM: wchwatal@luna.tuwien.ac.at
AF: Institute of Geodesy and Geophysics, Vienna University of Technology, Gusshausstrasse 27-29, Vienna, A-1040 Austria
AU: Rumpfhuber, E
EM: erumpf@luna.tuwien.ac.at
AF: Institute of Geodesy and Geophysics, Vienna University of Technology, Gusshausstrasse 27-29, Vienna, A-1040 Austria
AB: CELEBRATION 2000 and ALP 2002 are two large 3-D-refraction campaigns, which target the crustal and upper mantle structure in Central Europe. This study is based on these seismic data sets and concentrates on the area of the Eastern Alps region and the surrounding forelands and basins. The tectonic setting of the investigation area is characterized by a continent-continent-collision of the Adriatic and European plate and subsequently by a lateral extrusion eastwards to the Pannonian basin. As a consequence of these geodynamic processes we have to expect a complex structure of the lithosphere demanding a 3-D interpretation. The model parameters describing the crust by continuous velocity-depth functions and the depths and velocities of refractors (basis of sediments and Moho) are given in a 31x34-horizontal grid with 20 km spacing. The depth nodes of the velocity-depth functions have a spacing of approximately 1 km, starting with smaller intervals near the surface. Signal detection and stacking techniques were applied to the data in order to guarantee a reliable interpretation even in areas of degraded seismic energy transmission. The essential elements of these techniques are the STA/LTA algorithm, the sorting to common cell gathers with the common midpoint (CMP) or the source and receiver locations (SRC\&RCV) as sorting keys and the stacking to offset bins. The signal detection and stacking techniques and the related inversion methods will also be presented at this meeting (Brueckl et al., 2003). The offset stacks of CMP-sorted traces enhance significantly Pg-phases at large offsets, thus gaining greater penetration depths. A 3-D velocity depth model covering an area of about 300000 km2.was generated inverting these data by a 1-D tomographic approach at all grid points with sufficient coverage. The penetration depth of the method is 15 - 20 km in the Alps up to 40 km. As a test, the same method was applied to Sg-phases along one line. An S-wave velocity-depth section was created similar in penetration depth to the corresponding P-wave section and showing similar structures. The quality of Pn-arrivals in the Alpine area is generally low. By the generation of CMP-sorted and SRC\&RCV-sorted offset stacks and an inversion technique based on the delay time decomposition Pn-velocities and a reliable image of the delay times was generated. The significance of the model is checked by 3-D ray tracing. Brueckl, E., M. Behm and W. Chwatal, (2003). The application of signal detection and stacking techniques to refraction seismic data. Abstract submitted to AGU Meeting, San Francisco, 8-12 December 2003.
DE: 7205 Continental crust (1242)
DE: 7218 Lithosphere and upper mantle
SC: Seismology [S]
MN: 2003 Fall Meeting