IGMAS+: a success story of a 3-D potential field modelling software

In the context of research software sustainability, in this work we present the case of IGMAS+ (Interactive Gravity and Magnetic Application System) – a software tool for interactive 3-D numerical modelling, inversion, visualization and interpretation of potential fields together with some applications.

Modern workflows for geophysical interpretation and construction of 3-D data-constrained subsurface geophysical models in complex geological environments require software tools capable of handling multiple interdisciplinary and inhomogeneous input data, both seismic and non-seismic, like gravity and magnetics with their gradients, or magnetotelluric. These aspects imply big challenges not only in implementation and development of the modelling software, but also in organizing communication within the user community. A user of a research software often plays a role of a tester. Our joint goal as a research software community is to improve communication between developers and users, foster related technologies and overall culture of testing while using the research software.

Through the example of IGMAS+ we illustrate how a research software based on clear concepts with a well-established core algorithm can survive in the course of 40 years of development and still be useful, popular and demanded, at the same time being free for research and education purposes with a long-term plan to stay so. The software is largely used in creation of 3-D data-constrained subsurface structural density and susceptibility models at different spatial scales. Both large-scale models (thousands of square km) and regional (hundreds of square km), which we illustrate on several lithospheric-scale case studies, are important for understanding the drivers of geohazards. These models are necessary for efficient and sustainable extraction of resources, such as groundwater, deep geothermal energy or hydrocarbons, from sedimentary basins. Medium-scale models support studies on the usage of subsurface as thermal, electrical or material storage in the context of energy transformation. On the other hand, small-scale (tens of square km) models are largely used in applied geophysics, typically in sub-salt and sub-basalt settings. On the microscale (1 - 5 meters), the software presented here has also been used very successfully in the context of archaeological research and natural cavity localizations. Creation of all these models benefit a lot from the interactive modelling and inversion capabilities.

IGMAS+ is maintained and developed at the Helmholtz Centre Potsdam – GFZ German Research Centre by the effort of a research and development group limited by staff and time capacities. In these circumstances we find important to share our experience in organizing the development of the software and its documentation, the support of users, as well as our vision on the exchange of experience among the users.