Tomography Techniques And a Near Surface Model In the Andes

In this work we apply 2-dimensional seismic tomography techniques to determine the velocity model of the near surface strata in data from the Catatumbo area in Colombia, a zone of complex subsurface. Seismic tomography includes linear and non-linear techniques. Within the linear ones there are the Algorithmic Reconstruction Technique and the Simultaneous Iterative Reconstruction Technique, which require initial velocity models very near to the true velocity to ensure exactness and convergence. On the other side, the non-linear techniques have better theoretical principles and are less based on the initial model, but perhaps require more computational resources. The techniques used are applied to only refraction data. The ray tracing needed by the tomographic algorithms is performed using a hybrid technique based in the minimum travel time problem of graph theory and the ray bending technique. With these tomographic techniques it is also possible to obtain a velocity model of deep strata.