Geophysical Journal International Geophys. J. Int. (2014) 196, 1827–1843 doi: 10.1093/gji/ggt496 Advance Access publication 2014 January 2 Non-linear partial derivative and its De Wolf approximation for non-linear seismic inversion Ru-Shan Wu1 and Yingcai Zheng1,2 1Modeling and Imaging Laboratory, Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA. E-mail:
[email protected] 2Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139,USA Accepted 2013 December 6. Received 2013 December 5; in original form 2013 August 10 Downloaded from SUMMARY We demonstrate that higher order Frechet´ derivatives are not negligible and the linear Frechet´ derivative may not be appropriate in many cases, especially when forward scattering is involved for large-scale or strong perturbations (heterogeneities). We then introduce and derive the non- linear partial derivative including all the higher order Frechet´ derivatives for the acoustic wave http://gji.oxfordjournals.org/ equation. We prove that the higher order Frechet´ derivatives can be realized by consecutive applications of the scattering operator and a zero-order propagator to the source. The full non-linear partial derivative is directly related to the full scattering series. The formulation of the full non-linear derivative can be used to non-linearly update the model. It also provides a new way for deriving better approximations beyond the linear Frechet´ derivative (Born ap- proximation). In the second part of the paper, we derive the De Wolf approximation (DWA; multiple forescattering and single backscattering approximation) for the non-linear partial derivative. We split the linear derivative operator (i.e.