Main Article Content
In most of the deep seismic reflection and refraction surveys, the data acquisition is performed using irregular receiver and source spacings, due to the field conditions. In this study, I analyzed a field seismic reflection dataset recorded along a crooked profile that crossed the southeastern Carpathians (the Vrancea zone). The seismic section, obtained after the data processing, is clean, without clear reflections.. The finite-difference and the ray-tracing modelings were used to explain the lack of reflections on the seismic section. Both types of modeling were performed along straight and crooked profiles. The geometry for straight line is regular, meaning geophones spaced at 100 m and sources spaced at 1000 m. The geometry for crooked lines was defined using the field receiver and source (x,y)-coordinates. The velocity model used in modeling was build using the velocities obtained after the inversion of the first-arrival travel-times picked on the field records. The finite-difference modeling showed that the irregular geometry and complex geology affect the continuity of the reflections on the seismic sections. The ray-tracing modeling showed that the non-uniform seismic illumination is due to more the complex geology of the subsurface than the irregular geometry.