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Variation of crustal mass over the Australian region

Created 20/01/2026

Updated 20/01/2026

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Seismic refraction surveys in Australia and nearby marine areas provide data on crustal velocities and layer thicknesses. The averages of these at various places have been used to estimate a density-depth structure. By applying corrections for average elevation and free-air gravity, a crustal mass deficiency (CMD) is calculated for each site; this characterizes a standard crustal column with zero elevation and zero free-air anomaly, which is considered to be in isostatic equilibrium over a mantle of uniform density 3.32 t/m^3. The CMD ranges from about 13 kt/m^2 in the south-west of the continent, to about 21 in parts of Queensland; marine values range from 15 to 17 kt/m^2. The variations imply that isostasy on a broad scale is not complete at the base of the crust. As the gravity field indicates that departures from isostasy are comparatively small, compensation must occur partly in the mantle.

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Title Variation of crustal mass over the Australian region
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/9fc43c1d-c6ff-4299-8da0-ecb57b00ce24
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        110.0,
        -44.0
      ],
      [
        156.0,
        -44.0
      ],
      [
        156.0,
        -9.0
      ],
      [
        110.0,
        -9.0
      ],
      [
        110.0,
        -44.0
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Data.gov.au