Peter, D. and Tape, C. and Boschi, L. and Woodhouse, J. H. (2007) Surface wave tomography: global membrane waves and adjoint methods. Geophysical Journal International, 171 (3). pp. 1098-1117. ISSN 0956-540X http://resolver.caltech.edu/CaltechAUTHORS:PETgji07
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We implement the wave equation on a spherical membrane, with a finite-difference algorithm that accounts for finite-frequency effects in the smooth-Earth approximation, and use the resulting 'membrane waves' as an analogue for surface wave propagation in the Earth. In this formulation, we derive fully numerical 2-D sensitivity kernels for phase anomaly measurements, and employ them in a preliminary tomographic application. To speed up the computation of kernels, so that it is practical to formulate the inverse problem also with respect to a laterally heterogeneous starting model, we calculate them via the adjoint method, based on backpropagation, and parallelize our software on a Linux cluster. Our method is a step forward from ray theory, as it surpasses the inherent infinite-frequency approximation. It differs from analytical Born theory in that it does not involve a far-field approximation, and accounts, in principle, for non-linear effects like multiple scattering and wave front healing. It is much cheaper than the more accurate, fully 3-D numerical solution of the Earth's equations of motion, which has not yet been applied to large-scale tomography. Our tomographic results and trade-off analysis are compatible with those found in the ray- and analytical-Born-theory approaches.
|Additional Information:||© 2008 The Authors. Journal compilation © 2008 RAS. Accepted 2007 July 23. Received 2007 June 15; in original form 2007 August 18. We thank Domenico Giardini for his support and encouragement, Yann Capdeville and Jeroen Tromp for their many insightful comments. We are grateful to Göran Ekström for making his dispersion database available to us. We would also like to thank T. Tanimoto, B. Romanowicz, G. Laske and an anonymous reviewer for critical and constructive comments. Funding for this project is provided by the European Commission’s Human Resources and Mobility Program Marie Curie Research Training Network SPICE Contract No. MRTN-CT-2003-504267. Carl Tape’s master thesis (Tape 2003) is available at http://www.gps.caltech.edu/∼carltape|
|Subject Keywords:||adjoint methods • Born approximation • membrane waves • scattering theory • seismic tomography • surface waves|
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|Deposited On:||14 Jan 2009 21:47|
|Last Modified:||26 Dec 2012 10:43|
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