Gravity and magnetics#

Potential-field methods. They respond to density and magnetic susceptibility rather than to water, so they sit further from the hydrological question than the other methods here; what they contribute is the geometry the water moves through, over areas too large to cover with a ground survey.

What you can do#

Inspect an anomaly and separate the regional field from the residual.
Forward model the response of buried bodies, including prisms, spheres and dipoles.
Compact 3D inversion for density contrast or susceptibility.
Joint gravity and magnetics inversion on a shared mesh.

Required inputs#

A column table of station coordinates with the observed gravity disturbance or magnetic anomaly, and, for magnetics, the inducing field parameters. Two field datasets ship with the package: a Bushveld gravity disturbance and a British aeromagnetic anomaly, both under examples/data/Gravity_Magnetics.

Typical outputs#

A separated regional and residual field, and a 3D property model on a tensor mesh with the data it reproduces.

Choose a workflow#

Your goal	Start here
Invert a gravity or magnetic survey	Ex. Gravity and Magnetics Processing and Inversion
See what these methods add beside ERT, seismic and EM	Ex. Hydrology to Multi-Geophysics Responses

Desktop support#

Desktop Studio has a gravity and magnetics processing module.

Python examples#

Ex. Gravity and Magnetics Processing and Inversion: inspect the anomalies, forward model and run compact 3D inversion on both bundled datasets.
Ex. Hydrology to Multi-Geophysics Responses: the potential-field response of a hydrological profile, beside the responses of the other methods.

from PyHydroGeophysX.inversion import invert_gravmag

result = invert_gravmag(x, y, value, kind="gravity", detrend=1)

Relevant API#

Forward Module for gravity_prism, gravity_sphere, magnetic_dipole and forward_bodies.
Inversion Module for invert_gravmag and JointGravityMagneticsInversion.
Data Processing Module for the table readers and the regional-residual separation.

Limitations and optional dependencies#

Inversion runs on SimPEG and discretize with a usable sparse solver, all installed by the geophysics extra:

pip install "pyhydrogeophysx[geophysics]"

When that stack is missing, invert_gravmag raises InversionBackendUnavailable rather than falling back silently; the forward routines still run, since they need only NumPy.

Potential-field data constrain density and susceptibility, not saturation. Use these methods for structure, and read the water content from ERT, EM or seismic.