Australian National Gravity Grid with Tilt Image

Geoscience Australia's National Gravity Compilation 2019 integrates approximately 1.8 million gravity observations, including ground stations and airborne surveys totaling 451,000 line kilometers. The dataset includes a de-trended global isostatic residual (DGIR) tilt image processed via Fourier transform to highlight geological edges. It combines data from government, industry, and research sources collected from the 1940s to 2019.

Use Cases

• Detect edges of geological units by analyzing the tilt filter derived from the DGIR grid.
• Interpret subsurface geological structure using the processed gravity anomaly data.
• Map regional density variations from the Complete Bouguer Anomaly (CBA) data underlying the grid.
• Assess data resolution by comparing areas with ground station spacing (down to 1 km) and airborne line spacing (0.5 to 2.5 km).

Strengths

• Integrates approximately 1.8 million gravity observations from multiple sources.
• Includes 345,000 line km of airborne gravity and 106,000 line km of airborne gravity gradiometry data for enhanced resolution.
• Grid has a defined cell size of 0.00417 degrees (approximately 435 meters).
• Data quality was checked by GA geophysicists to ensure it is fit-for-purpose.

Limitations

• Ground station spacing is inconsistent, varying from 11 km to less than 1 km across the continent.
• Offshore data is sourced from a global grid (v28.1), which may have different resolution and accuracy than the primary Australian data.

Provenance

Source

Geoscience Australia Data

Collection Method

Processed from the 2019 Australian National Gravity Grids B series, combining ground observations, airborne surveys, and global offshore data.

Time Range

1940s to 2019

Freshness

Data reflects observations in the Australian National Gravity Database as of September 2019.

Geography

Australia and its continental margins