Australian Free Air Gravity Anomaly Grid at 435m Resolution

A free air gravity anomaly grid for Australia and its continental margins measures variations in gravitational acceleration due to subsurface rock density. The grid integrates nearly 1.4 million ground stations from the national database and offshore data, with station spacing from less than 1 km to 11 km. It was compiled by Geoscience Australia using data from government, industry, and research sources collected from the 1940s to September 2019.

Use Cases

• Model subsurface geological structure by interpreting the free air anomaly values in gravity units (gu).
• Map density contrasts in the crust and upper mantle using the 0.00417-degree cell resolution grid.
• Integrate gravity data with other geophysical surveys for joint inversion using the defined continental margin spatial coverage.
• Analyze spatial gravity trends for tectonic feature identification across Australia's varied station spacing regions.

Strengths

• Integrates nearly 1.4 million gravity stations from the national database.
• Provides continental coverage of Australia and its margins at a 435-meter (0.00417-degree) cell resolution.
• Combines decades of ground data (1940s-present) with v28.1 of the Scripps/NOAA/NGA global gravity grid.

Limitations

• Ground station density is uneven, with spacing varying from under 1 km to 11 km across the continent.
• The core observational data is static as of September 2019, lacking more recent measurements.

Provenance

Source

Geoscience Australia, Australian National Gravity Database, and Scripps Institution of Oceanography/NOAA/NGA global grid.

Collection Method

Ground gravity observations processed via standard methods and checked by GA geophysicists, gridded into a free air anomaly raster.

Time Range

Ground observations from the 1940s to September 2019.

Freshness

Grid compilation is from 2019; metadata was last updated in April 2026.

Geography

Australia and its continental margins.