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The terrestrial lithosphere represents the external solidified cover of the Earth with a high heterogeneity due to structural and petrologic variations on both vertical and horizontal plane. Being the center of geodynamics processes with effects felt both on geological and human time scale, numerous studies tried to decipher its structure and composition. Realistic models elaboration of this structure and its composition at different scales of detail was constructed in most of the cases on the elastic properties of the rocks that compose this cover. The most used parameter in such studies is the speed (of propagation) of the longitudinal seismic body waves (Vp). Theirs size depends on the mineralogical composition, structure, fluid saturation, pressure and temperature. That is why numerous national/international has been conducted in the past decades with the proposed objectives of creating models that mimics the shallow cover structure at different depth scales and zones (having as main parameter Vp).
The propagation velocities frequently associated with seismic waves amplitude constitutes the base for defining algorithms for processing seismic data and afterwards structural and stratigraphic interpretation of the results. In order to conduct seismological and tectonic studies is necessary to build models of seismic velocities that consists the primary base for elaborating geodynamical and geotectonic models. They later indicate the presence of seismic active areas. Bidimensional velocity models, using direct or inverse approach to the data, on different transect all over the world has been obtained from deep refracted seismic studies. The velocity values obtained represent the mean average or linearly increasing with depth. Details and resolution studies of the obtained velocity models can be verified and tested by integrating previous industrial lines or borehole data that intersects or lies within the profiles. Until now there has not been conducted such study. Consequently, the major objective of this project is to construct bi- and tri-dimensional models of the Vp seismic waves velocity distribution using as input data seismic records from reflection or refraction lines (either shallow or deeper) records available on the Romanian territory. The shallow velocity values will be verified using seismo-acoustic well logs data. It will be built velocity distribution models correspondent to the main Romanian tectonic units: the Moesian Platform, the Moldavian Platform the Pannonian Basin and Transylvanian Basin. It will be selected for analyses, processing and interpretation the seismic records which will offer the targeted seismic lines density for elaborating the velocity models. The depth velocity values sampling interval will be defined strictly dependent on the maximum proposed depth of investigation. In the final stage all the data will be integrated into a regional (country) scale tri-dimensional model. During the elaboration of the model it will be used also information depicted from international or national publications. By extrapolation there will be resolved the blank areas. Major tectonic units limits will be pinned down using horizontal velocity gradient analyses and concurrent geophysical and geological existent information. Also it will determinate to the smallest detail zones of high seismic hazard correspondent to previously known crustal scale seismically active zones from different areas: Vrancea Window, Banat, Maramures, North Dobrogea, Peceneaga-Camena crustal fault zone, Intramoesian Fault, South Transylvania, Campulung-Fagaras Area, etc..
The velocity distribution model will be considered a valuable toll for later seismic studies, tectonic modeling or hydrocarbon investigation and last but not the least for detailed analyses of earthquakes and theirs accompanying effects (observed via national seismic observation network from National Institute of Earth Physics).
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