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Computation of complete synthetic seismograms for laterally heterogeneous models using the direct solution method. Geophys
 J. Int
, 1997
"... pute complete synthetic seismograms and their partial derivatives for laterally heterogeneous models in spherical coordinates. The methods presented in this paper are well suited to conducting waveform inversion for 3D Earth structure. No assumptions of weak perturbation are necessary, although su ..."
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Cited by 14 (5 self)
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pute complete synthetic seismograms and their partial derivatives for laterally heterogeneous models in spherical coordinates. The methods presented in this paper are well suited to conducting waveform inversion for 3D Earth structure. No assumptions of weak perturbation are necessary, although such approximations greatly improve computational efficiency when their use is appropriate. An example calculation is presented in which the toroidal wavefield is calculated for an axisymmetric model for which velocity is dependent on depth and latitude but not longitude. The wavefield calculated using the DSM agrees well with wavefronts calculated by tracing rays. To demonstrate that our algorithm is not limited to weak, aspherical perturbations to a spherically symmetric structure, we consider a model for which the latitudedependent part of the velocity structure is very strong. Key words: synthetic seismograms, body waves, surfaces waves, lateral heterogeneity 1
Upper mantle anisotropy and coupledmode longperiod surface waves
 w,/2Q, = w,q,/2
, 1993
"... We investigate surface wave propagation effects caused by P and Swave velocity anisotropy and its orientation in the upper mantle. We compare coupledmode synthetic seismograms, constructed from sums of free oscillations for different types of upper mantle models, in order to understand better the ..."
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Cited by 12 (1 self)
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We investigate surface wave propagation effects caused by P and Swave velocity anisotropy and its orientation in the upper mantle. We compare coupledmode synthetic seismograms, constructed from sums of free oscillations for different types of upper mantle models, in order to understand better the observable aspects of anisotropy and its fast direction in the earth. Our calculations suggest that upper mantle anisotropy, which is not transversely isotropic, of few per cent can generate significant waveform anomalies in longperiod seismic records of 020 mHz. Those anomalies are termed ‘quasiLove ’ waves and are caused by spheroidaltoroidal freeoscillation coupling. Large quasiLove waveforms are difficult to produce with levels of isotropic heterogeneity consistent with global tomographic models of the mantle. Coupledmode waveform anomalies in longperiod seismic records at a single station can be used to diagnose the presence of anisotropic structure in the upper mantle. Because J, OT,r coupling pairs have weak sensitivity to aspherical wavenumbers s < I /  [’I, and II 1’1 increases with frequency for f> 4 mHz, smoother/rougher structure generates longer/shorterperiod fundamentalbranch
The COSY Project: Verification of Global Seismic Modeling Algorithms
"... Progress in understanding the details in the global 3D seismic velocity structure rests on the assumption that we can accurately model seismic wave propagation (e.g. travel times, waveforms, etc.) through heterogeneous 3D Earth models. While for spherically symmetric models (quasi)analytical solu ..."
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Cited by 7 (2 self)
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Progress in understanding the details in the global 3D seismic velocity structure rests on the assumption that we can accurately model seismic wave propagation (e.g. travel times, waveforms, etc.) through heterogeneous 3D Earth models. While for spherically symmetric models (quasi)analytical solutions are available for the verification of numerical algorithms this is not the case for general heterogeneous models. It is therefore desirable to establish global 3D test models and verified reference seismograms, which allow us to access the accuracy of these algorithms in a quantitative way. Prior to a workshop held on this issue at the 1997 IASPEI Meeting, a 3D test model was handed out to various groups and synthetic seismograms returned. This workshop was the initiation of the COSY Project (COmparison of global SYnthetic seismogram techniques) which aims at establishing a a WWW page (http://www.itg.cam.ac.uk/COSY) where the test models and seismograms as well as some of the used al...
unknown title
, 1999
"... www.elsevier.comrlocaterpepi The COSY Project: verification of global seismic modeling algorithms ..."
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www.elsevier.comrlocaterpepi The COSY Project: verification of global seismic modeling algorithms
unknown title
, 1999
"... www.elsevier.comrlocaterpepi The COSY Project: verification of global seismic modeling algorithms ..."
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www.elsevier.comrlocaterpepi The COSY Project: verification of global seismic modeling algorithms