MTGeophysics.jl: A software repository for magnetotelluric research and applications

The magnetotelluric (MT) method uses natural electromagnetic field variations to image subsurface electrical resistivity at depths ranging from tens of metres to hundreds of kilometres.It is widely used in geophysical exploration for natural resources, including minerals, geothermal energy, and groundwater, as well as in the characterisation of sites for CO 2 storage and in studies of crustal and lithospheric structure.The MT inverse problem is, however, inherently nonunique: many distinct resistivity models reproduce the observations equally well.Conventional practice nonetheless reports a single regularised model, with no quantitative measure of its uncertainty.MTGeophysics.jl is a Julia package developed to address this limitation.Its principal aim is the quantification of uncertainty in MT model building, advancing interpretation from a single deterministic model, through an ensemble of plausible models, towards the full posterior distribution (Figure 1).The package also provides tools for data analysis, mesh generation, masking, forward modelling, inversion, model analysis and visualisation for MT research and applications.