Skip to content

i.gravity

Bouguer gravity anomaly computation (full slab).

i.gravity gravity_obs=name elevation=name latitude=name flight_azimuth=name flight_velocity=name slab_density=name terrain_corr=name output=name [--overwrite] [--verbose] [--quiet] [--qq] [--ui]

Example:

i.gravity gravity_obs=gravity_obs elevation=dem latitude=lat flight_azimuth=flight_azimuth flight_velocity=flight_velocity slab_density=slab_density terrain_corr=terrain_corr output=name

grass.script.run_command("i.gravity", gravity_obs="gravity_obs", elevation="dem", latitude="lat", flight_azimuth="flight_azimuth", flight_velocity="flight_velocity", slab_density="slab_density", terrain_corr="terrain_corr", output, overwrite=None, verbose=None, quiet=None, superquiet=None)

Example:

gs.run_command("i.gravity", gravity_obs="gravity_obs", elevation="dem", latitude="lat", flight_azimuth="flight_azimuth", flight_velocity="flight_velocity", slab_density="slab_density", terrain_corr="terrain_corr", output="name")

grass.tools.Tools.i_gravity(gravity_obs="gravity_obs", elevation="dem", latitude="lat", flight_azimuth="flight_azimuth", flight_velocity="flight_velocity", slab_density="slab_density", terrain_corr="terrain_corr", output, overwrite=None, verbose=None, quiet=None, superquiet=None)

Example:

tools = Tools()
tools.i_gravity(gravity_obs="gravity_obs", elevation="dem", latitude="lat", flight_azimuth="flight_azimuth", flight_velocity="flight_velocity", slab_density="slab_density", terrain_corr="terrain_corr", output="name")

This grass.tools API is experimental in version 8.5 and expected to be stable in version 8.6.

Parameters

gravity_obs=name [required]
    Name of the observed gravity map [mGal]
    Default: gravity_obs
elevation=name [required]
    Name of the elevation map [m]
    Default: dem
latitude=name [required]
    Name of the latitude map [dd.ddd]
    Default: lat
flight_azimuth=name [required]
    Name of the flight azimuth map (clockwise from North) [dd.ddd]
    Default: flight_azimuth
flight_velocity=name [required]
    Name of the flight velocity [kph]
    Default: flight_velocity
slab_density=name [required]
    Name of the slab density [kg/m3]
    Default: slab_density
terrain_corr=name [required]
    Name of the terrain correction map []
    Default: terrain_corr
output=name [required]
    Name of the Bouguer gravity anomaly [mGal]
--overwrite
    Allow output files to overwrite existing files
--help
    Print usage summary
--verbose
    Verbose module output
--quiet
    Quiet module output
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

gravity_obs : str, required
    Name of the observed gravity map [mGal]
    Used as: input, raster, name
    Default: gravity_obs
elevation : str, required
    Name of the elevation map [m]
    Used as: input, raster, name
    Default: dem
latitude : str, required
    Name of the latitude map [dd.ddd]
    Used as: input, raster, name
    Default: lat
flight_azimuth : str, required
    Name of the flight azimuth map (clockwise from North) [dd.ddd]
    Used as: input, raster, name
    Default: flight_azimuth
flight_velocity : str, required
    Name of the flight velocity [kph]
    Used as: input, raster, name
    Default: flight_velocity
slab_density : str, required
    Name of the slab density [kg/m3]
    Used as: input, raster, name
    Default: slab_density
terrain_corr : str, required
    Name of the terrain correction map []
    Used as: input, raster, name
    Default: terrain_corr
output : str, required
    Name of the Bouguer gravity anomaly [mGal]
    Used as: output, raster, name
overwrite : bool, optional
    Allow output files to overwrite existing files
    Default: None
verbose : bool, optional
    Verbose module output
    Default: None
quiet : bool, optional
    Quiet module output
    Default: None
superquiet : bool, optional
    Very quiet module output
    Default: None

gravity_obs : str | np.ndarray, required
    Name of the observed gravity map [mGal]
    Used as: input, raster, name
    Default: gravity_obs
elevation : str | np.ndarray, required
    Name of the elevation map [m]
    Used as: input, raster, name
    Default: dem
latitude : str | np.ndarray, required
    Name of the latitude map [dd.ddd]
    Used as: input, raster, name
    Default: lat
flight_azimuth : str | np.ndarray, required
    Name of the flight azimuth map (clockwise from North) [dd.ddd]
    Used as: input, raster, name
    Default: flight_azimuth
flight_velocity : str | np.ndarray, required
    Name of the flight velocity [kph]
    Used as: input, raster, name
    Default: flight_velocity
slab_density : str | np.ndarray, required
    Name of the slab density [kg/m3]
    Used as: input, raster, name
    Default: slab_density
terrain_corr : str | np.ndarray, required
    Name of the terrain correction map []
    Used as: input, raster, name
    Default: terrain_corr
output : str | type(np.ndarray) | type(np.array) | type(gs.array.array), required
    Name of the Bouguer gravity anomaly [mGal]
    Used as: output, raster, name
overwrite : bool, optional
    Allow output files to overwrite existing files
    Default: None
verbose : bool, optional
    Verbose module output
    Default: None
quiet : bool, optional
    Quiet module output
    Default: None
superquiet : bool, optional
    Very quiet module output
    Default: None

Returns:

result : grass.tools.support.ToolResult | np.ndarray | tuple[np.ndarray] | None
If the tool produces text as standard output, a ToolResult object will be returned. Otherwise, None will be returned. If an array type (e.g., np.ndarray) is used for one of the raster outputs, the result will be an array and will have the shape corresponding to the computational region. If an array type is used for more than one raster output, the result will be a tuple of arrays.

DESCRIPTION

i.gravity calculates the Bouguer gravity anomaly (after Mussett and Khan).
Bouguer anomaly computation require:

  • g_obs=observed gravity
  • freeair_corr=free air correction
  • bouguer_corr=bouguer correction
  • terrain_corr=terrain correction
  • latitude_corr=latitude correction
  • eotvos_corr=eotvos correction

NOTES

  • International Gravity Formula (mGal), lambda=latitude (dd)
  • Eotvos correction (mGal), v=velocity (kph), lambda=latitude (dd), alpha=direction of travel measured clockwise from North
  • Free air Correction (mGal), h=height (m)
  • Bouguer Correction (mGal), rho=density of slab (Mg/m3), h=height (m)

For more details on the algorithms see [1].

SEE ALSO

i.latlon

REFERENCES

[1] Mussett, A.E. and Khan, M.A, M.A. Looking into the Earth: An Introduction to Geological Geophysics.

AUTHOR

Yann Chemin, University of London at Birkbeck, United Kingdom.

SOURCE CODE

Available at: i.gravity source code (history)
Latest change: Thursday May 29 16:46:38 2025 in commit 1350f28