**Model with a lenticular inclusion (LEN)****Preliminary Reference Earth Model (PREM)****Model with homogeneous layers (ELF1, MI)****Salt dome models (SD1 and SD2)****Model with interface slitted by a curved vertical fault (SLIT)****Western Bohemia a priori model (WB2)****Model of real geological structure (L7)****Gridded 2-D Marmousi model (MAR)****Unconformity 2-D model (U2D)****1-D model (RM)****Weakly anisotropic model (QI)****Sample synthetic 3-D model (98)****1-D anisotropic "twisted crystal" model (TC)****Simple smooth 3-D model (N2)****2-D representation of the Laguerr random medium (RAN)****2-D model with a salt body (HES)****1-D constant velocity gradient model (VGR)****SEG/EAGE Salt Model (SAL)****2-D model Pluto 1.5 (PLU)****Computation of R/T coefficients****Models of the Cotton Valey site (CV)****Model with planar interfaces (EX)**

- 3-D model with a lenticular inclusion is a synthetic demo model for SW3D package MODEL.
- VRML and GOCAD representations and snapshots of the model
*Examples with history files:*- Transforming surfaces and velocity sections into VRML or GOCAD. Computing 3-D P-wave velocity cube (GOCAD Voxet). len-mod.h
- Generating colour PostScript files with the velocity sections across the model. len-grd.h
- Generating 3-D grids of values of velocity and of indices of complex blocks. len-grid.h
- Performing initial-value ray tracing of rays shot in a single vertical plane from the point source. len-crti.h
- Performing 3-D two-point ray tracing for a point source. Adding source, receivers and two-point rays into VRML or GOCAD representation of the model with surfaces. len-crt.h
- Transforming wavefronts and two-point rays into VRML. len-wf.h
- 3-D two-point ray tracing for the plane wave incident at the bottom of the model. lenb-crt.h
- 3-D two-point ray tracing for exploding reflector (zero-offset rays). lenz-crt.h
- Controlled initial-value ray tracing in the model followed by 3-D interpolation of travel times within ray cells. leni-mtt.h
- Initial-value ray tracing of the cone of rays in the model followed by calculation of the derivatives of the travel times with respect to the model B-spline coefficients. Adding source, receivers and rays into VRML or GOCAD representation of the model with surfaces. len-cone.h
- Performing shortest path calculation of the first arrival travel times and the corresponding rays on a rectangular grid in the model (network ray tracing). len-net.h
- Simple demonstration history file used to debug and test the inversion programs. The data to be inverted are created by discretization of model LEN. The same model is then obtained by the overdetermined least-square inversion. len-inv.h

- Brief description of data files for packages FORMS, MODEL, CRT, NET
- Related papers

**Preliminary Reference Earth Model (PREM)** - 3-D B-spline approximation of the model PREM (Dziewonski and Anderson 1981), specified in geographical spherical coordinates.
*Examples with history files:*- Generating PostScript files with the sections across the model PREM displaying the velocities and indices of complex blocks. prem-grd.h
- Tracing pPKP+pPKiKP, pPKIKP, PKP+PKiKP and PKIKP rays in spherical coordinates. prem-crt.h

- Guide to the input data for the complete ray tracing program.
- Data files for packages FORMS, MODEL, CRT

**Model with homogeneous layers (ELF1, MI)** - 3-D model with four homogeneous layers separated by dipping plane interfaces.
- VRML and GOCAD representations and snapshots of the model
*Examples with history files and perl scripts:*- Transforming model with homogeneous layers separated by plane interfaces (ELF1) into VRML or GOCAD. elf1-mod.h
- Performing 3-D two-point ray tracing for moving source and receiver profile. elf1a.pl, elf1b.pl, elf1c.pl

- Data files for packages FORMS, MODEL, CRT
- Related papers

**Salt dome model (SD1) and dislocated salt dome model (SD2)** - Sample 3-D synthetic models of a salt dome.
- VRML and GOCAD representations and snapshots of the model
*Examples with history files:*- Data files for packages FORMS, MODEL
- Related papers

**Model with interface slitted by a curved vertical fault (SLIT)** - Image of the model
- Data files for packages FORMS, MODEL
- Related papers

**Western Bohemia a priori model (WB2)** - 3-D Western Bohemia a priori model prepared as a test model resembling the conditions of refraction seismic measurements performed in Western Bohemia.
- VRML and GOCAD representations and snapshots of the model
*Examples with history files:*- Data files for packages FORMS, MODEL
- Related papers

**Model of real geological structure (L7)** - 3-D model of real geological structure provided by Institut Francais du Petrole. Present version contains only two of seven structural interfaces.
- VRML and GOCAD representations and snapshots of the model
*Examples with history files:*- Transforming interfaces in model L7 into VRML or GOCAD. l7-mod.h
- Generating PostScript files with the sections across model L7 displaying the P-wave velocities.
- Two-point ray tracing in model L7, adding rays to the VRML or GOCAD files with interfaces.

- Data files for packages FORMS, MODEL, CRT
- Related papers

**Gridded 2-D Marmousi model and INRIA bench-mark versions of the 2-D Marmousi model (MAR)** - 2-D Marmousi model is based on real geological structure (Versteeg & Grau 1991).
*Examples with history files:*- INRIA bench-mark versions of the Marmousi model
- Generating PostScript files showing the P wave velocity sections in both INRIA bench-mark versions of the Marmousi model. mar-grd.h
- Calculating travel times in the INRIA Marmousi models
- Smoothing the Marmousi model for Gaussian-packet migrations.
- Optimizing the shape of Gaussian beams for migrations.
- Zero-offset ray tracing in the smoothed Marmousi model.

- Data files for packages FORMS, MODEL, CRT
- Related papers

**Unconformity 2-D model (U2D)** - Unconformity 2-D model by Cormier and Mellen (1984).
*Examples with history files:*- Generating PostScript file with the section across the model U2D displaying the P-wave velocity. u2d-grd.h
- Performing 2-D two-point ray tracing and generating synthetic seismograms. u2d-ss.h
- Comparing ray-theory and finite-difference synthetic seismograms. u2d-fd.h
- Generating system of equations for travel-time inversion. u2d-inv.h

- Data files for packages FORMS, MODEL, CRT, FD
- Related papers

**1-D model (RM)** - 1-D model RM consists of a thin homogeneous low-velocity layer covering homogeneous halfspace.
*Examples with history files:*- Comparing ray-matrix and 2-D finite differences seismograms in 1-D model RM. rm-fd.h

- Data files for packages FORMS, MODEL, CRT, RM, FD
- Related papers

**Weakly anisotropic model (QI)** - Weakly anisotropic model QI for comparison of synthetic seismograms with package ANRAY.
*Examples with history files:*- Computing coupling ray theory and four kinds of quasi-isotropic ray theory synthetic seismograms. Calculating second-order perturbations of travel times. qi-ss.h
- Running history file 'qi-ss.h' for four different models, which differ in the degree of anisotropy. Calculating travel times by programe ANRAY, and comparing the results of ANRAY and CRT. qi-ss4m.h
- Test of anisotropic common S wave ray tracing in different models. qi-acr.h
- Computing isotropic, anisotropic, and coupling ray theory synthetic seismograms in the model with a very weak anisotropy. qih-ss.h

- Data files for packages FORMS, MODEL, CRT
- Related papers

**Sample synthetic 3-D model (98)** - Sample synthetic 3-D model created during the technical session of the SW3D consortium meeting in June 1998. The model is composed of three layers separated by two interfaces. A salt body in the middle layer is bounded by a spherical interface.
- VRML and GOCAD representations and snapshots of the model
*Examples with history files:*- Sample computations in the model 98 (generating PostScript figures of velocity sections, transforming surfaces into VRML or GOCAD, calculating multi-valued travel times, generating synthetic seismograms)

- Data files for packages FORMS, MODEL, CRT
- Related papers

**1-D anisotropic "twisted crystal" model (TC)** - 1-D anisotropic "simplified twisted crystal" and "oblique twisted crystal" models.
*Examples with history files:*- Analytically computing propagator matrices in model "simplified twisted crystal", and comparing the results with Green functions computed by CRT. Comparing the analytical solution with finite-difference solution in the frequency domain. Generating synthetic seismograms and plotting a figure of comparison of different ray-tracing methods. tc.h
- Analytically computing exact propagator matrix in model "oblique twisted crystal", and comparing the results with different quasi-isotropic approximations of the coupling ray theory computed by CRT. Generating synthetic seismograms and plotting a figure of the comparison. tco.h

- Data files: one-purpose Fortran codes, data for packages FORMS, MODEL, CRT and for the one-purpose codes
- Description of files related to the finite-difference solution
- Related papers

**Simple smooth 3-D model (N2)** - Simple smooth 3-D model to demonstrate network ray tracing in the paper by Klimes and Kvasnicka (1994).
*Examples with history files:*- Calculating velocity isolines in 2-D sections. Computing rays and travel times by network ray tracing. n2-net.h

- Brief description of data files
for packages MODEL, NET

**2-D representation of the Laguerr random medium (RAN)** *Examples with history files:*- Generating a 2-D representation of the Laguerr random medium and calculating first arrival travel times. ran-net.h

- Data files for packages FORMS, NET
- Related papers

**2-D model with a salt body (HES)** - 2-D model of real geological structure with a salt body by Scott Morton of the Amerada Hess Corporation.
*Examples with history files:*- Data files for packages FORMS, MODEL, CRT
- Related papers

**1-D constant velocity gradient model (VGR)** - 1-D constant velocity gradient model by Pascal Podvin (Podvin and Lecomte 1991).
*Examples with history files:*- Brief description of data files for packages FORMS, CRT, NET
- Related papers

**SEG/EAGE Salt Model (SAL)** - 3-D SEG/EAGE Salt Model with features similar to those of the U.S. Gulf of Mexico salt structure (Aminzadeh et al. 1997).
- VRML and GOCAD representations and snapshots of the model smoothed for ray tracing
*Examples with history files:*- Data files for packages FORMS, MODEL, CRT

**2-D model Pluto 1.5 (PLU)** - 2-D model Pluto 1.5 of real geological structure with a salt bodies created by Smaart Joint Venture.
*Examples with history files:*- Data files for packages FORMS, MODEL, CRT

**Computation of R/T coefficients** *Examples with history files:*- Data files for package FORMS
- Related papers

**Models of the Cotton Valey site (CV)** - Several models of a real structure in the Cotton Valey site based on a simultaneous inversion of the data by James Rutledge.
*Examples with history files:*- Data files for packages FORMS, MODEL, CRT

**Model with planar interfaces (EX)** - 3-D analytical model with five homogeneous layers separated by dipping plane interfaces.
- Sample synthetic 3-D model created during the technical session of the SW3D consortium meeting in June 2004. The model is composed of five layers separated by three planar interfaces and one interface composed of two horizontal and two tilted planes.
- VRML and GOCAD representations and snapshots of the reflected two-point rays calculated in the model
*Examples with history files:*- Data files for packages FORMS, MODEL, CRT

- Aminzadeh, F., Brac, J., Kunz, T. (1997): 3-D Salt and Overthrust Models. SEG/EAGE 3-D Modeling Series No.1., Soc. Explor. Geophysicists, Tulsa.
- Cormier, V.F. & Mellen, M.H. (1984): Application of asymptotic ray theory to vertical seismic profiling. In: Toksoz, M.N. & Stewart, R.R. (eds.), Vertical Seismic Profiling: Advanced Concepts, pp. 28-44, Geophysical Press, London.
- Dziewonski, A.M. & Anderson, D.L. (1981): Preliminary reference
Earth model. Phys. Earth planet. Inter.,
**25**, 297. - Klimes, L. and Kvasnicka, M. (1994): 3-D network ray tracing.
Geophys. J. int.,
**116**, 726-738. - Podvin, P. & Lecomte, I. (1991): Finite difference computation
of traveltimes in very contrasted velocity models: a massively
parallel approach and its associated tools.
Geophys.J.int.,
**105**, 271-284. - Versteeg, R.J. & Grau, G. (1991): The Marmousi experience. Proc. EAGE workshop on Practical Aspects of Seismic Data Inversion (Copenhagen, 1990), Eur. Assoc. Explor. Geophysicists, Zeist.