Software

**EdgeFEM3DwPrec ver. 2017**,
Release March 2018. Release March 2018. The program provides
frequency-domain finite-element modeling of electric field
responses in 3D anisotropic conductive medium. The program user
interface is the same as EdgeFEM3D (Cai and Zhdanov, 2016). The
crucial difference between the two programs is that EdgeFEM3DwPrec
is leveraged with Green’s Function (GF) and contraction operator
(CO) preconditioners (Yavich and Zhdanov, 2016), while EdgeFEM3D
uses simple Jacobi preconditioner. Consequently, EdgeFEM3DwPrec
provides much faster modeling than EdgeFEM3D. The medium is
assumed to be formed by a layered background and finite number of
rectangular inclusions. The secondary field approach (Zhdanov,
2017) is implemented; thus sources are incorporated via the
background field. The latter is computed with the green3d module.
The finite-element grid is assumed to be rectangular and
nonuniform. We appreciate that more general hexahedral grids might
be more attractive for modeling of complex geological structures;
we thus plan to extend this code respectively in the future..

Authors: Nikolay Yavich, Hongzhu Cai, and Michael S. Zhdanov.

References:

Cai, H., and M. S. Zhdanov, 2016, EdgeFEM3D
user manual.

Yavich, N., and M. S. Zhdanov, 2016,
Contraction pre-conditioner in finitedifference electromagnetic
modelling, Geophysical Journal International, 206, 1718 - 1729.

Zhdanov, M. S., 2017, Foundations of
geophysical electromagnetic theory and methods: Elsevier.

**FEMTet3D ver. 2016**,
Release March 2017. The FEMTet3D is a MATLAB software package for
3D numerical modeling of controlled source electromagnetic (CSEM)
data using the edge-based finite element method (Cai et al.,
2015). The package solves the low frequency Maxwell’s equations
for an anomalous electric field (Zhdanov, 2009). The software
adopts unstructured tetrahedral discretization of the subsurface
to simulate the complex geometries. The algorithm is capable of
solving the diffusive EM problem in anisotropic medium. The
background electromagnetic field is calculated using CEMI Green3D

software which is based on the fast Hankel transform (Anderson,
1989; Guptasarma and Singh, 1997). The sparse finite element
system of equations is solved using MKL Pardiso, which is a
parallelized multifrontal direct solver. Please refer to the
FEMTet3D manual and examples for running the algorithm.

Authors: Hongzhu Cai, Martin Cuma, and Michael Zhdanov.

References:

Anderson, W. L., 1989, A hybrid fast Hankel
transform algorithm for electromagnetic modeling: Geophysics, 54,
263-266.

Guptasarma, D., and B. Singh, 1997, New digital
linear filters for Hankel J0 and J1 transforms: Geophysical
Prospecting, 54, 263-266.

Zhdanov, M. S., 2009, Geophysical
electromagnetic theory and methods: Elsevier.

**PIE3D ver. 2015**,
Release March 2016. The PIE3D ver. 2016 is parallel EM forward
modeling software based on the IE method. PIE3D ver. 2016 is
designed for distributed memory machines (e.g., PC clusters) and
is portable on any computer that supports message passing
interface (MPI). This code simulates frequency-domain EM responses
of multiple-domain (MD) 3D anomalous resistivity structures in a
horizontally layered medium.

For this release the functionality remains the same, except for a
few minor bug fixes both in PIE3D and in GREEN3D. The major
improvement is providing binaries for the Windows and Linux 64
bit, including all the external libraries and tools. Therefore
PIE3D can run without any effort spent on installing external
packages. The binaries have been tested on Windows 7 and 10 and on
CentOS 6 and 7, Ubuntu 14.04, and Debian 8.

Authors: Martin Cuma and Michael Zhdanov

References:

Endo, M., M. Čuma, and M. S. Zhdanov, 2009,
Application of a multiple-domain, integral-equation method for 3D
electromagnetic modeling in complex geoelectrical structures:
Proceedings of the Annual Meeting, Consortium for Electromagnetic
Modeling and Inversion, 27-48.

Endo, M., M. Čuma, and Zhdanov, M. S., 2009,
Large-scale electromagnetic modeling for multiple inhomogeneous
domains: Communications in Computational Physics, 6, 269-289.

Hursán, G., and M. S. Zhdanov, 2002,
Contraction integral equation method in three-dimensional
electromagnetic modeling: Radio Science, 37 (6), 1089, doi:
10.1029/ 2001RS002513.

Yoshioka, K., and M. S. Zhdanov, 2005,
Electromagnetic forward modeling based on the integral equation
method using parallel computers: Proceedings of the Annual
Meeting, Consortium for Electromagnetic Modeling and Inversion,
25-44.

Yoshioka, K., and M. S. Zhdanov, 2006, Modeling
large-scale geoelectrical structures with inhomogeneous
backgrounds using the integral equation method: application to the
bathymetry effects in marine CSEM data: Proceedings of the Annual
Meeting, Consortium for Electromagnetic Modeling and Inversion,
159-180.

Zhdanov, M. S., S. K. Lee, and K. Yoshioka,
2006, Integral equation method for 3D modeling of electromagnetic
fields in complex structures with inhomogeneous background
conductivity: Geophysics, 71 (6), G333-G345, doi:
10.1190/1.2358403.

Ueda, T., and M. S. Zhdanov, 2006, Fast
numerical modeling of multitransmitter electromagnetic data using
multigrid quasi-linear approximation: IEEE Transactions in
Geoscience and Remote Sensing, 44, 1428-1434.

Zhdanov, M. S., 2002, Geophysical inverse
theory and regularization problems: Elsevier.

**EdgeHexTop****
ver. 2015**, release March 2016. The EdgeHexTop is a MATLAB
software package for 3D numerical modeling of controlled source
electromagnetic (CSEM) data using edge-based finite element method
(Cai et al., 2015). The package solves the low frequency Maxwell's
equation for a secondary electric field (Zhdanov, 2009). Compared
to our previous release, this version of the code uses a distorted
hexahedral mesh to account for topography and bathymetry effects.
The algorithm is capable of solving the diffusive EM problem in an
anisotropic medium. The background electromagnetic field is
calculated using our Green3d software, which is based on the fast
Hankel transform (Anderson, 1989; Guptasarma and Singh, 1997). The
sparse finite element system of equations is solved using the
quasi-minimum residual method with a simple and effective Jacobian
preconditioner.

Authors: Hongzhu Cai and Michael S. Zhdanov.

References:

Anderson, W. L., 1989, A hybrid fast hankel
transform algorithm for electromagnetic modeling: Geophysics, 54,
263-266.

Cai, H., B. Xiong, M. Han, and M. S. Zhdanov,
2014, 3D controlled-source electromagnetic modeling in anisotropic
medium using edge-based finite element method: Computers &
Geosciences, 73, 164-176.

Guptasarma, D., and B. Singh, 1997, New digital
linear filters for Hankel J0 and J1 transforms: Geophysical
Prospecting, 54, 263-266.

Zhdanov, M. S., 2009, Geophysical
electromagnetic theory and methods: Elsevier.

**FDIE3D ver. 2015**,
release March 2016. The FDIE3D is a MATLAB software package for 3D
numerical modeling and controlled source electromagnetic (CSEM)
data using the hybrid finite difference (FD) and integral equation
(IE) method (Yoon et al., 2015). This hybrid FD-IE method solves
the low frequency Maxwell's equations for anomalous electric
fields using FD approximation on the staggered grid (Newman and
Alumbaugh, 1995), and calculates the EM fields at the receiver
positions based on the Green's tensor approach. This approach
makes it possible to compute the fields at the receivers
accurately without mesh refinement near the receiver or the source
positions. The sparse finite difference system of equations is
solved using the quasi-minimum residual method with a Jacobian
preconditioner.

Authors: Daeung Yoon and Michael S. Zhdanov.

References:

Newman, G. A., and D. L. Alumbaugh, 1995,
Frequency-domain modelling of airborne electromagnetic responses
using staggered finite differences: Geophysical Prospecting, 43,
1021--1042.

Yoon, D., M. S. Zhdanov, H. Cai, and A.
Gribenko, 2015, A hybrid finite difference and integral equation
method for modeling and inversion of marine CSEM data: Consortium
for Electromagnetic Modeling and Inversion, Proceedings of 2015
Annual Meeting.

**GREEN3D**,
release March 2010. The MatLab shell of the Fortran 77 library
GREENLIB for computing the normal fields and volume integrals of
electromagnetic Green's tensors. This program is designed to help
the development of electromagnetic modeling and inversion
programs. It is an easy-to-use MATLAB function which can be called
up anywhere in the MATLAB environment. Using this library, the
software developer is freed from coding the excessively complex
algorithms for Green's tensors and different electromagnetic
fields in a layered medium.

Author: Gabor Hursan

References:

Xiong, Z., 1992, EM modeling of three-dimensional structures by
the method of system iteration using integral equations,
Geophysics, **57**, 1556-1561.

Zhdanov, M. S., and G. V. Keller, 1994, The geoelectrical methods
in geophysical exploration: Elsevier, 873 pp.

G. Hursan, 1999, A Fortran 77 Library for Computing the Normal
Fields and Volume Integrals of Electromagnetic Green's Tensors:
Proceedings of the CEMI 1999 Annual Meeting.

**INTEM3DQLIP ver. 2014**,
release March 2015. INTEM3DQLIP_2014 is designed for frequency
domain electromagnetic (EM) modeling of three-dimensional
anisotropic geoelectrical structures embedded in horizontally
layered earth based on the integral equation (IE) method (Hursán
and Zhdanov, 2002). The following sources can be modeled using
this program::

- plane wave propagating vertically toward the Earth
(magnetotelluric);

- current bipoles along the x, y, and z directions;

- horizontal rectangular loop:

- horizontal circular loop;

- moving horizontal loops;

- magnetic dipoles oriented in the x, y, and z directions.

Authors: Masashi Endo and Michael Zhdanov

Hursan, G., and M. S. Zhdanov, 2002, Contraction integral
equation method in three-dimensional electromagnetic modeling:
Radio Sci., 37 (6), 1089,
doi: 10.1029/ 2001RS002513.

Zhdanov, M. S., 2002, Geophysical inverse theory and
regularization problems: Elsevier.

Zhdanov, M. S., 2009, Geophysical electromagnetic theory and
methods: Elsevier.

**EdgeFEM3D ver. 2014**,
release March 2015. The EdgeFEM3D is a MATLAB software package for
3D numerical modeling of controlled source electromagnetic (CSEM)
data using edgebased finite element method (Cai et al., 2014). The
package solves Maxwell’s equations for the anomalous electric
field (Zhdanov, 2009). The algorithm is capable of solving the
diffusive EM problem in anisotropic medium. The background
electromagnetic field is calculated using CEMI GREEN3D software,
which is based on the fast Hankel transform (Anderson, 1989;
Guptasarma and Singh, 1997). The sparse finite element system of
equations is solved using quasi minimum residual method with a
Jacobian preconditioner.

Authors: Hongzhu Cai and Michael Zhdanov

Anderson, W. L., 1989, A hybrid fast hankel transform algorithm
for electromagnetic modeling: Geophysics, 54, 263-266.

Cai, H., B. Xiong, M. Han, andM. S. Zhdanov, 2014, 3D
controlled-source electromagnetic modeling in anisotropic medium
using edge-based finite element method: Computers &
Geosciences, 73, 164-176.

Guptasarma, D., and B. Singh, 1997, New digital linear filters for
Hankel J0 and J1 transforms: Geophysical Prospecting, 54, 263-266.

Zhdanov, M. S., 2009, Geophysical electromagnetic theory and
methods: Elsevier.

**TSEMRSA ver. 2017**,
Release March 2018. Subsurface targets, hydrocarbon reservoirs or
ores and mineral deposits for example, are usually characterized
by different electric conductivities with the bedrocks or
sediments. An induced anomalous electromagnetic field will be
generated by the targets when they are excited by an external
electromagnetic field. The anomalous field manifests itself as a
fast and good indication of the location and range of the
subsurface targets. However, the anomalous field is usually weak
and unrecognizable due to strong background field and
environmental noise. The TSEMRSA software package is specially
designed to enhance the response from the targets and provide a
fast imaging tool to locate subsurface targets laterally. The
concept of synthetic aperture is employed in this package to
uplift the signal from the targets. The current 2017 version of
the TSEMRSA software package is specially designed for the survey
configuration of marine towed streamer electromagnetic method, but
with the prospect of supporting airborne electromagnetic survey in
future versions.

Authors: Xiaolei Tu, Michael S. Zhdanov, and Daeung
Yoon.

References:

Yoon, D. and M. S. Zhdanov, 2014, An optimal synthetic aperture
method for the creation of directional sensitivity and removal of
the airwave effect in MCSEM data: in SEG 84th Annual Meeting,
Expanded Abstracts, 685 - 690.

Yoon, D. and M. S. Zhdanov, 2015, Optimal synthetic aperture
method for marine controlled source EM surveys: IEEE Geoscience
and Remote Sensing Letters, 12 (2), 414 - 418.

Zhdanov, M. S., D. Yoon, and J. Mattsson, 2017, Rapid imaging of
towed streamer EM Data using the optimal synthetic aperture
method: IEEE Geoscience and Remote Sensing Letters, 14 (2), 262 -
266.

**MultiGrav3D ver. 2017**,
Release March 2018. The MultiGrav3D is a PGI CUDA Fortran based
software package for 3D multinary inversion of gravity and/or full
tensor gradiometry (FTG) data. The code uses the multinary
transformation of the model parameters to explicitly exploit the
sharp contrasts of the density between the host media and
anomalous targets in the inversion of gravity data. The multinary
transformation is based on the given values of density and error
functions. We also provide the option of an adaptive technique for
selecting the corresponding standard deviations specifically
designed for the multinary inversion of the field data. The code
can also be run as a traditional inversion tool using minimum norm
support by setting the standard deviation as some large value, for
example, 0.5. The code is written in CUDA Fortran, which requires
Nvidia graphics cards and CUDA toolkit installed. The code must be
run with the PGI Fortran compiler.

Authors: Wei Lin and Michael S. Zhdanov.

References:

Zhdanov, M. S., and L. Cox, 2013, Multinary inversion of
geophysical data: Proceedings of the Annual Meeting of the
Consortium for Electromagnetic Modeling and Inversion, The
University of Utah, 125-136.

Zhdanov, M. S., 2015, Inverse theory and applications in
geophysics: Elsevier

Zhdanov, M. S., and W. Lin, 2017, Adaptive multinary inversion of
gravity and gravity gradiometry data: Geophysics, 82(6), G101 -
G114.

**MT3D ver. 2017**,
Release March 2018. The MT3D software package performs 3D
inversion of magnetotelluric (MT) data. FullMT impedance tensor
(Zxx, Zxy, Zyx, and Zyy) with the option of adding a magnetic
tipper (Wzx and Wzy) can be inverted over inhomogeneous geological
formations for 3D conductivity distribution and distortion matrix.
This problem is associated with computing the 3D electromagnetic
(EM) fields and Fréchet derivative used in minimization. We use a
rigorous integral equation (IE) method for forward modeling
(Zhdanov, 2002), and quasi-Born approximation for Fréchet
derivative calculation (Gribenko and Zhdanov, 2007). MT data
inversion is an ill-posed problem. To obtain a stable solution we
apply the Tikhonov regularization method (Zhdanov, 2002, 2015).
The inversion is based on the Gauss-Newton method in data space
(Gribenko and Zhdanov, 2017).

Authors: Alexander V. Gribenko, andMichael S.
Zhdanov.

References:

Gribenko, A. V., and M. S. Zhdanov, 2007, Rigorous 3d inversion of
marine CSEM data based on the integral equation method:
Geophysics, 72(2), 229 - 254.

Gribenko, A. V., andM. S. Zhdanov, 2017, Regularized Gauss-Newton
method of nonlinear geophysical inversion in the data space:
Applications to 3D magnetotelluric inversion: 87th Annual
International Meeting, SEG, Expanded Abstracts, 1126 - 1130.

Zhdanov, M. S., 2002, Geophysical inverse theory and
regularization problems: Elsevier.

Zhdanov, M. S., 2015, Inverse theory and applications in
geophysics: Elsevier.

Zhdanov, M. S., 2017, Foundations of geophysical electromagnetic
theory and methods: Elsevier.

**JOINT3D ver. 2016**,
Release March 2017. The JOINT3D is a MATLAB software package for
3D joint inversion of potential field and airborne electromagnetic
(EM) data using Gramian constraints (Zhdanov et al., 2012). The
packages is capable for either direct or structural correlation
between two physical properties, e.g., density and log of
conductivity, magnetic susceptibility, and log of conductivity. In
the potential field forward modeling, we discretize the modeling
domain into a set of rectangular prisms and evaluate the volume
integral in each prism using single-point Gaussian integration.
The airborne EM forward modeling and Fréchet computation are based
on the integral equation method (Hohmann, 1975) and quasi-born
approximation (Gribenko and Zhdanov, 2007), respectively. The
package is compatible with both minimum norm and maximum smooth
stabilizers. We solve the joint inversion problem using the
regularized conjugate gradient method (Zhdanov, 2002). Please
refer to the JOINT3D manual and examples for running the
algorithm.

Authors: Yue Zhu, Michael Jorgensen, and Michael S.
Zhdanov

References:

Gribenko, A., and M. Zhdanov, 2007, Rigorous 3D inversion of
marine CSEM data based on the integral equation method:
Geophysics, 72, WA73-WA84.

Hohmann, G. W., 1975, Three dimensional induced polarization and
electromagnetic modeling: Geophysics, 40, 309-324.

Zhdanov, M. S., 2002, Geophysical inverse theory and
regularization problems: Elsevier.

Zhdanov, M. S., A. Gribenko, and G.Wilson, 2012, Generalized joint
inversion of multimodal geophysical data using Gramian
constraints: Geophysical Research Letters, 39, L09301.

**GRAVMTBASE ver. 2016**,
Release March 2017. The GRAVMTBASE is a MATLAB joint inversion
software package for depth to basement estimation using gravity
and electromagnetic (e.g., MT) data (Cai and Zhdanov, 2015a,
2015b; Cai and Zhdanov, 2016). The software using Cauchy-type
integral transform and integral equation methods for the modeling
of gravity and MT data, respectively. The algorithm discretizes
the interface between the sediments and basement rocks. In the
inversion, the depth to basement and the physical property
contrast (e.g., density contrast, conductivity values) between
sediment and basement will be recovered simultaneously. The joint
inversion can reduce the uncertainty comparing to the separate
inversion of either gravity or MT data.

Please refer to the GRAVMTBASE manual and examples for running the
algorithm.

Authors: Hongzhu Cai and Michael Zhdanov

References:

Cai, H. and Zhdanov, M., 2015a. Application of Cauchy-type
integrals in developing effective methods for depth-to-basement
inversion of gravity and gravity gradiometry data: Geophysics, 80
(2), G81-G94.

Cai, H. and Zhdanov, M.S., 2015b. Modeling and inversion of
magnetic anomalies caused by sediment-basement interface using
three-dimensional Cauchy-type integrals: IEEE Geoscience and
Remote Sensing Letters, 12 (3), 477-481.

Cai, H. and Zhdanov, M., 2016. Three-Dimensional inversion of
magnetotelluric data for the sediment-basement interface: IEEE
Geoscience and Remote Sensing Letters, 13 (3), 349-353.

**JOINT3D ver. 2015**,Released
March 2016. The JOINT3D software package performs 3D joint
inversion of gravity and magnetic data. It works for any
combination of the gravity (Gx, Gy, Gz, Gxx, Gyy, Gzz, Gxy, Gzx,
Gzy, Gd) and magnetic components (TMI, Hx, Hy, Hz). The joint
inversion code uses the Gramian constraints (Zhdanov et al., 2012)
to enhance either direct or structural correlations between two
physical properties, which are the density and magnetic
susceptibility or the density and magnetization vector, depending
on the existence or not of remanent magnetization. We discretize
the modeling domain into a set of rectangular prisms and evaluate
the volume integral in each prism using single-point Gaussian
integration in the forward modeling and Fréchet computation. The
code is compatible with both minimum norm and maximum smooth
stabilizers. We solve the joint inversion problem using the
regularized conjugate gradient method (Zhdanov, 2002).

Authors: Yue Zhu and Michael S. Zhdanov.

References:

Zhdanov, M. S., 2002, Geophysical inverse theory and
regularization problems: Elsevier.

Zhdanov, M. S., 2015, Inverse theory and applications in
Geophysics: Elsevier.

Zhdanov, M. S., A. Gribenko, and G. Wilson, 2012, Generalized
joint inversion of multimodal geophysical data using Gramian
constraints: Geophysical Research Letters, 39, L09301.

**MCSEM3D ver. 2012**,
Release March 2013. Matlab software package for 3D inversion of
the marine controlled source electromagnetic (MCSEM) data. The
predicted data are calculated rigorously by the PIE3D integral
equation (IE) modeling code. The fast Fréchet derivative
computation is based on the quasi-Born (QB) approximation
(Gribenko et al., 2010). The standard approach of minimizing the
Tikhonov parametric functional (Tikhonov and Arsenin, 1977) is
realized in the code. The regularized conjugategradient method
with re-weightings and adaptive regularization is used for
parametric functional minimization (Zhdanov, 2002). At the first
stage, the code uses a minimum norm stabilizer, minimum gradient
stabilizers, or their combination, which produces smooth
conductivity distributions (Gribenko and Zhdanov, 2011). At the
consequent stages (re-weightings), the user has a choice of
minimum norm, minimum support (Portniaguine and Zhdanov, 1999),
minimum vertical support (Zhdanov et al., 2007) stabilizers, or
their combination. Appropriate selection of the stabilizing
functional allows the user to find a solution with sharp
geoelectrical boundaries.

Unlike the previous versions, the code allows several transmitter
lines with inline MCSEMdata. The code uses the parallel version of
the 3D electromagnetic (EM) forward modeling code (PIE3D). MCSEM3D
is written in the MATLAB language for the versions 2006b or later.
MATLAB license is required to run MCSEM3D. MCSEM3D is platform
independent.,

Authors: Alexander Gribenko, Daeung Yoon, and Michael S.
Zhdanov

References:

Hursán, G., and M. S. Zhdanov, 2002,
Contraction integral equation method in three-dimensional
electromagnetic modeling: Radio Science, 37 (6), 1089, doi:

10.1029/ 2001RS002513.

Gribenko, A., and M. S. Zhdanov, 2010, Rigorous 3D inversion of
marine CSEM data based on the integral equation method:
Geophysics, 72, WA73.

Gribenko, A., and M. S. Zhdanov, 2011, Joint inversion of MT and
MCSEM data in off-shore exploration: Proceedings of 2011 CEMI
Annual Meeting.

Gribenko, A., L. Wan, and M. S. Zhdanov, 2010, Three-dimensional
inversion of magnetotelluric data for complex resistivity:
Proceedings of 2010 CEMI Annual

Meeting, 269-294.

Gribenko, A., A. M. Green, M. Cuma, and M. S. Zhdanov, 2010,
Efficient 3D inversion of MT data using integral equations method
and the receiver footprint approach:

application to the large-scale inversion of the EarthScope MT
data: 80th Annual InternationalMeeting, SEG, Expanded Abstracts,
655-659, doi:10.1190/1.3513865.

Portniaguine, O., and M. S. Zhdanov, 1999, Focusing geophysical
inversion images: Geophysics, 64, 874-887.

Tikhonov, A. N., and V. Y. Arsenin, 1977, Solution of ill-posed
problems: V. H. Winston and Sons.

Zhdanov, M. S., 2002, Geophysical inverse theory and
regularization problems: Elsevier.

Zhdanov, M.S., 2009, Geophysical electromagnetic theory and
methods: Elsevier.

Zhdanov, M. S., A. Gribenko, and M. Cuma, 2007, Regularized
focusing inversion of marine CSEM data using minimum
vertical-support stabilizer: 77th Annual International Meeting,
SEG, Expanded Abstracts, 579-583.

**MCSEM_MT3D ver. 2014. **Release
March 2015. MATLAB software package for joint 3D inversion of the
marine controlled source electromagnetic (MCSEM) and
magnetotelluric (MT) data. The predicted data are calculated
rigorously by the PIE3D integral equation (IE) modeling code. The
fast Fréchet derivative computation is based on the quasi-Born
(QB) approximation (Gribenko and Zhdanov, 2007). The standard
approach of minimizing the Tikhonov parametric functional
(Tikhonov and Arsenin, 1977) is realized in the code. The
regularized conjugate-gradient method with re-weightings and
adaptive regularization is used for the parametric functional
minimization (Zhdanov , 2002). At the first stage the code uses a
minimum norm stabilizer, minimum gradient stabilizers,or their
combination, which produces smooth conductivity distributions
(Gribenko and Zhdanov, 2011). At the consequent stages
(re-weightings) the user has a choice of minimum norm, minimum
support (Portniaguine and Zhdanov, 1999), minimum vertical support
(Zhdanov et al., 2007) stabilizers, or their combination.
Appropriate selection of the stabilizing functional allows the
user to find a solution with sharp geoelectrical boundaries. An
adaptive data weighting technique is implemented in the code.

Authors: Alexander Gribenko and Michael S.
Zhdanov

References:

Hursán, G., andM. S. Zhdanov, 2002, Contraction integral equation
method in three-dimensional electromagneticmodeling: Radio
Science, 37 (6), 1089, doi:10.1029/2001RS002513.

Gribenko, A., and M. S. Zhdanov, 2007, Rigorous 3D inversion of
marine CSEM data based on the integral equation method:
Geophysics, 72, WA73.

Gribenko, A., and M. S. Zhdanov, 2011, Joint inversion of MT and
MCSEM data in off-shore exploration: Proceedings of 2011 CEMI
Annual Meeting.

Gribenko, A., L. Wan, and M. S. Zhdanov, 2010, Three-dimensional
inversion of magnetotelluric data for complex resistivity:
Proceedings of 2010 CEMI Annual Meeting, 269-294.

Portniaguine, O., and M. S. Zhdanov, 1999, Focusing geophysical
inversion images: Geophysics, 64, 874-887.

Tikhonov, A. N., and V. Y. Arsenin, 1977, Solution of ill-posed
problems: V. H. Winston and Sons.

Zhdanov, M. S., 2002, Geophysical inverse theory and
regularization problems: Elsevier.

Zhdanov, M.S., 2009, Geophysical electromagnetic theory and
methods: Elsevier

Zhdanov, M. S., A. Gribenko, and M. ˇCuma, 2007, Regularized
focusing inversion of marine CSEM data using minimum
vertical-support stabilizer: 77th Annual International Meeting,
SEG, Expanded Abstracts, 579-583.

**PF3D ver. 2011**,
Release March 2012. The PF3D ver. 2011 is a MATLAB software
package for 3D modeling and inversion of potential field data
which includes magnetic field, magnetic gradient tensor
components, gravity field, and gravity gradient tensor components.
The code is designed for 3D inversion of the data collected on a
variable surface, including the option for joint inversion of the
different gravity or magnetic field and tensor field components.
For inversion, the code uses the approach known as the re-weighted
regularized conjugant gradient method, or RRCG method, with
focusing stabilizers to produce compact geophysical images. It
also utilizes a technique to naturally impose model constraints by
computing iterations in the space of logarithmic model parameters.

Authors: Martin Cuma and Michael S. Zhdanov

References:

Portniaguine, O., and M. S. Zhdanov, 1999,
Focusing geophysical inversion images: Geophysics, 64, 874-887.

Zhdanov, M. S., 2002, Geophysical inverse
theory and regularization problems: Elsevier.

**GG3Dmigration ver. 2013**,
Release March 2014.The GG3Dmigration ver. 2014 is a MATLAB
software package for migration of the gravity and/or gravity
gradiometry data in order to image a 3D density distribution. The
gravity and/or gravity gradiometry data can be collected on a
variable surface. The major novel feature of the code is the
ability to select an arbitrary combination of gravity field and
gravity tensor components and migrate them jointly. The migration
can be done on a large scale and within an arbitrary selected
domain. The software package includes the source code, user manual
and examples. Also, it includes a code to produce the
cross-section image for a convenience. The software is easy to
maintain and to use.

Authors: Le Wan and Michael S. Zhdanov

References:

Zhdanov, M. S., X. Liu, G. A. Wilson, and L.
Wan, 2011, Potential field migration for rapid imaging of gravity
gradiometry data: Geophysical Prospecting, 59, 1052--1071.

**CauchyGrav3D ver. 2014**,
Release March 2015. The CauchyGrav3D ver. 2014 is a MATLAB
software package for 3D modeling and inversion of gravity data
caused by a density contrast interface model. The code uses a
novel approach based on 3D analogs of Cauchy type integrals for
the modeling and inversion of gravity and gravity gradiometry data
caused by the density contrast model (Zhdanov, 1988; Cai and
Zhdanov, 2014, 2015). The code can be used in Windows or Linux
machine with MATLAB installed. For this release, the density
contrast is assumed to be a given constant in the inversion. The
code outputs the depth to basement. This package contains two main
programs for forward modeling and inversion. The program
Cauchy3DFWD is the program for forward modeling, while the program
Cauchy3DInv is for inversion.

Authors: Hongzhu Cai and Michael S. Zhdanov

References:

Cai, H., and M. S. Zhdanov, 2014, Modeling and inversion of
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Cai, H., and M. S. Zhdanov, 2015, Application of Cauchy-type
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Zhdanov, M. S., 1988, Integral transforms in geophysics:
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