Full waveform inversion (FWI) in transversely isotropic media usually requires abundant a priori information, like well data and smoothness assumptions, to make the FWI converge to a plausible solution. The proper model parameterization in transversely isotropic (TI) media with a vertical symmetry axis (VTI) can alleviate some of these limitations. Considering the limitations of our field data ...

In their studies of transversely isotropic media with a vertical symmetry axis (VTI media), Alkhalifah and Tsvankin observed that, to a high numerical accuracy, the normal moveout (NMO) velocity for dipping reflectors as a function of ray parameter p depends mainly on just two parameters, each of which can be determined from surface P-wave observations. They substantiated this result by using t...

In transversely isotropic media with a vertical axis of symmetry (VTI media), we can represent the image in vertical time, as opposed to depth, thus eliminating the inherent ambiguity of resolving the vertical P-wave velocity from surface seismic data. In this new (x − τ )-domain, the raytracing and eikonal equations are completely independent of the vertical P-wave velocity, on the condition t...

[1] The lowermost mantle beneath Central America has anisotropic seismic velocity structure manifested in shear wave splitting of signals from South American earthquakes recorded at North American broadband recording stations. Prior studies of deep mantle anisotropy in this region have characterized the structure as having vertical transverse isotropy (VTI), which is sufficient to explain a gen...

A new wavefield extrapolation method has been developed that allows the propagation of waves in an anisotropic medium. The anisotropic medium considered here is transversely isotropic (TI) with an axis of symmetry. Our method applies an asymmetric explicit correction filter after the normal isotropic extrapolation operator. It is stable and suitable for laterally varying TI media. This new sche...

Abstract Anisotropy of subsurface media can affect the seismic wave travel time estimates, and then imaging target regions. To calibrate effect anisotropy, a VTI (transverse isotropy with vertical symmetry axis) least-squares reverse-time migration (LSRTM) algorithm is used. However, if data contains noise especially outliers, high-quality images cannot be produced by LSRTM based on an L2 norm....

In transversely isotropic media with a vertical axis of symmetry (VTI media), we represent the image in vertical time, as opposed to depth, thus eliminating the inherent ambiguity of resolving the vertical P-wave velocity from surface seismic data. In this new (x±t)-domain, the ray tracing and eikonal equations are completely independent of the vertical P-wave velocity, with the condition that ...

I develop an implicit finite-difference migration method for vertical transversely isotropic (VTI) media with laterally varying anisotropy parameters. I approximate the dispersion relation of VTI media with a rational function series, the coefficients of which are estimated by least-squares optimization. These coefficients are functions of Thomsen anisotropy parameters. They are calculated and ...

We present 3D prestack map time migration in closed form for qP-, qSV-, and mode-converted waves in homogeneous transversely isotropic media with a vertical symmetry axis (VTI). As far as prestack time demigration is concerned, we present closed-form expressions for mapping in homogeneous isotropic media, while for homogeneous VTI media we present a system of four nonlinear equations with four ...

[1] Shear waves that traverse the lowermost mantle exhibit polarization anomalies and waveform complexities that indicate the presence of complex velocity structure above the core-mantle boundary. Synthetic seismograms for horizontally and vertically polarized shear waves (SH and SV, respectively) are computed using the reflectivity method for structures with low-velocity sheets (‘‘lamellae’’),...