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Global 3-D imaging of mantle electrical conductivity based on inversion of observatory C-responses-I. An approach and its verification

2012; Oxford University Press; Volume: 189; Issue: 3 Linguagem: Inglês

10.1111/j.1365-246x.2011.05349.x

1365-246X

Alexey Kuvshinov, Alexey Semenov,

Seismic Waves and Analysis

We present a novel frequency-domain inverse solution to recover the 3-D electrical conductivity distribution in the mantle. The solution is based on analysis of local C-responses. It exploits an iterative gradient-type method—limited-memory quasi-Newton method—for minimizing the penalty function consisting of data misfit and regularization terms. The integral equation code is used as a forward engine to calculate responses and data misfit gradients during inversion. An adjoint approach is implemented to compute misfit gradients efficiently. Further improvements in computational load come from parallelizing the scheme with respect to frequencies, and from setting the most time-consuming part of the forward calculations—calculation of Green′s tensors—apart from the inversion loop. Convergence, performance, and accuracy of our 3-D inverse solution are demonstrated with a synthetic numerical example. A companion paper applies the strategy set forth here to real data.