GMG is an open-source Graphical User Interface (GUI) designed principally for modelling 2D potential field (gravity and magnetic) profiles. The software also includes functions for loading XY data, seismic reflection SEGY data and exploration well horizons. The software therefore provides an integrated geological/geophysical interpretation package. It is anticipated that GMG will also be useful for teaching purposes.

Data I/O is made as simple as possible using space delimited ASCII text files.

The project was instigated after failing to find an adequate open-source option (in which the source code can be viewed and modified by the user) for performing 2D geophysical modeling tasks. Inspiration came from Fatiando a Terra and GMT.

NB: GMG is in development. Some documentation is incomplete and some features may not work as expected. If you experience any issues, please feel free to raise these on the issue tracker.

• Import and display observed topography, gravity and magnetic 2D profile data.
• Apply filters to observed data.
• Add and manipulate model layers (subsurface bodies) using a simple interactive interface.
• “Pinch out/snap” layers against adjacent layers.
• Calculate the predicted gravity anomaly produced by any combination of model layers.
• Calculate the predicted magnetic anomaly produced by any combination of model layers.
• Model magnetic anomalies using induced and/or remanent magnetism.
• Display well horizon tops.
• Display XY data (e.g., earthquake hypocenters, geological surface contacts or rays from a auxiliary velocity model).
• Import and display seismic reflection data.
• Export model data (e.g., predicted anomalies and layer geometries) as ASCII text files.
• Save model figures as vector or raster graphics in various formats (.png .ps .eps .pdf).

Note

gmg is written in Python 3 and can be installed using common python package managers conda (from conda-forge) or pip. Installation and launching of the software involves the use of a command line terminal, but this is minimal and should be manageable for a non-expert by following the instructions below.

Step 1: Install Miniforge

If you don't already use miniforge or anaconda for managing and installing python packages, then the simplest way to install gmg is to first install Miniforge (a minimal installer for Conda specifically for conda-forge).

This should ensure you can install all the dependencies required on any platform (Linux, Mac, Windows) using the Conda package manager.

Step 2: Create a new conda environment for gmg

It's best to create a new conda environment to use when running GMG. This will avoid any potential conflicts. e.g.:

conda create -n gmgpy

Where the -n flag dictates what you want to name the new environment (you can call the environment whatever you like but the documentation will use the name gmg-env).

On macOS and Linux this environment can then be activated using:

conda activate gmgpy

Or on Windows use::

activate gmgpy

Once the environment is activated any call to python will only "see" the packages install within the gmg-env environment. To deactivate the environment either close the terminal window or on macOS and Linux run:

conda deactivate

Or on Windows use:

deactivate

OS Support:

GMG is currently only tested on macOS Monterey, Ubuntu 22.04 Linux and Windows 11 operating systems. It is possible that issues may arise when trying to install on other distributions. Please raise any information regarding installation problems on github.

NB: conda-forge and pip packages are currently in development and not yet deployed

The gmg package is hosted on both conda-forge and PyPi (pip). It is highly recommended that you install gmg in a standalone conda environment using option 1 below. This is ensure you do not create any dependencies issues that may arise if you install system-wide using pip.

First, ensure your gmgpy conda environment is active. On macOS or Linux use:

source activate gmgpy

Or on Windows use:

activate gmgpy

Installation option using pip test

pip install -i https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple gmgpy

after installation, make sure you are using a terminal with your gmgpy environment active (i.e., conda activate gmgpy), then, gmg can be launched from your terminal command line using:

gmgpy

The splash screen and gmg model shell should appear. You can now begin using the software.

GMG is packaged with a tutorial dataset and benchmark demos. If you installed gmg using the recommended miniforge approach (as outlined above), then, the gmg package directory is likely located in a path similar to:

/Users/username/miniforge3/envs/gmgpy/lib/python3.X/site-packages/gmgpy

Within this directory are the two subdirectories:

 demos/
 tutorial/ 

These can be copied or moved to another location on your system or accessed from gmgpy directory when required. You can also download these directories from the gmg github docs/ directory.

The best way to get started is to read through the Documentation starting with the Manual and Demos then work your way through the Tutorial. These can also be found by launching gmg and then navigating to:

Help -> Documentation

Any contribution, big or small is welcome. Examples include:

1. Writing new code/functions.
2. Improving the user interface.
3. Submitting bug reports and spelling corrections.

They are all helpful!

Becoming a developer

The best way to become a developer is to create a folk of the github repository. You can then send a pull request once you are satisfied you want to share your modifications.

Suggestions & bug reporting

The best way to make a suggestion or open a bug report is to raise an issue on Github.

Please use the subject line:

GMG suggestion: "short suggestion description"
GMG bug report: "short bug description"

Please include as much detail as possible when describing the bug.

If you use GMG, please cite this github repository.