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DTSTAMP:20190719T085744Z
LOCATION:HG E 1.2
DTSTART;TZID=Europe/Stockholm:20190613T171500
DTEND;TZID=Europe/Stockholm:20190613T174500
UID:submissions.pasc-conference.org_PASC19_sess134_msa275@linklings.com
SUMMARY:Recent Numerical Advances in Revealing the Earth's Interior with F
 ull-Waveform Inversion
DESCRIPTION:Minisymposium\nSolid Earth Dynamics\n\nRecent Numerical Advanc
 es in Revealing the Earth's Interior with Full-Waveform Inversion\n\nBoehm
 , Krischer, Afanasiev, van Driel, Fichtner\n\nMulti-parameter tomographic 
 inversions using physically realistic 3D simulations and adjoint methods a
 re nowadays an established technique to reveal the inner structure of our 
 planet. Although numerous studies have shown the great potential of full-w
 aveform inversion, dealing with the inherent non-linearity and ill-posedne
 ss of the inverse problem and the ever-growing amounts of available data s
 till cause significant challenges. Starting from a matrix-free, performant
  and highly scalable spectral-element implementation to solve the equation
 s of motions, we focus this contribution on the necessary adjustments of t
 he inversion methods to provide a stable and computationally efficient wor
 kflow. To this end, we present a trust-region framework that allows us to 
 efficiently work on unstructured and distributed meshes, to impose additio
 nal constraints on the model and to use subsets of the data. We make use o
 f the L-BFGS approximation of the inverse Hessian with a built-in smoothin
 g filter based on an anisotropic and space-dependent diffusion operator th
 at includes spatially varying smoothing lengths and variable smoothing dir
 ections. We demonstrate the capability and efficiency of the inversion fra
 mework in several synthetic examples from local to global scale. Furthermo
 re, we showcase its application in ongoing work of a full waveform inversi
 on of the Australasian region.
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