ROBUST ELASTIC NONLINEAR WAVE-FORM INVERSION - APPLICATION TO REAL DATA

Nonlinear elastic waveform inversion has advanced to the point where it is now possible to invert real multiple-shot seismic data. The iterative gradient algorithm that we employ can readily accommodate robust minimization criteria which tend to handle many types of seismic noise better than the commonly used least-squares minimization criteria. Although there are many robust criteria from which to choose, we have tested only a few. In particular, the Cauchy criterion and the hyperbolic secant criterion perform very well. Although the real data set, which we invert using the sech criterion, is marine (pressure sources and receivers) and is very much dominated by unconverted P waves, we can, for the most part, resolve the short wavelengths of both P impedance and S impedance. -from Authors