Fu, LeiSymes, William W.2017-05-052017-05-052017Fu, Lei and Symes, William W.. "An adaptive multiscale algorithm for efficient extended waveform inversion." <i>Geophysics,</i> 82, no. 3 (2017) Society of Exploration Geophysicists: R183-R197. http://dx.doi.org/10.1190/geo2016-0426.1.https://hdl.handle.net/1911/94195Subsurface-offset extended full-waveform inversion (FWI) may converge to kinematically accurate velocity models without the low-frequency data accuracy required for standard data-domain FWI. However, this robust alternative approach to waveform inversion suffers from a very high computational cost resulting from its use of nonlocal wave physics: The computation of strain from stress involves an integral over the subsurface offset axis, which must be performed at every space-time grid point. We found that a combination of data-fit driven offset limits, grid coarsening, and low-pass data filtering can reduce the cost of extended inversion by one to two orders of magnitude.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlefull-waveform inversionvelocity analysisimaginghttp://dx.doi.org/10.1190/geo2016-0426.1