Elastic wavefield inversion by the alternating update method

Full-waveform inversion is a promising tool for a wide range of imaging scenario, in that it has the potential to harness the non-linear relationship between model parameters and data (as opposed to traditional methodologies), in order to produce truly quantitative results. Non-linearity represents an opportunity, in this sense, but it also begets local minimum issues when gradientbased optimization is employed. In this thesis, we are particularly interested in the quantitative estimation of the elastic parameters of the earth, such as compressibility, shear modulus, and density. If successful, this procedure brings geophysical imaging closer to the ultimate step of seismic exploration: the retrieval of pore pressure and rock properties. This would be of direct use for, say, the oil and gas industry. Other interesting applications are the description of the near surface/near ocean bottom, as a way to reduce drilling hazards, or non-destructive inspection of defects in oil and gas pipes, when ultrasounds are employed.