Australian Gravity Anomaly Grid With Half Vertical Derivative

Gravity anomaly data measures subsurface rock density variations across Australia and its continental margins. The grid incorporates nearly 1.4 million ground stations and over 450,000 line kilometers of airborne gravity and gradiometry surveys, compiled by Geoscience Australia from data collected since the 1940s. This specific 2019 national compilation grid applies a half vertical derivative to the complete spherical cap Bouguer anomaly.

Use Cases

• Map geological structures by interpreting the half vertical derivative of Bouguer anomalies to highlight density contrasts.
• Integrate offshore bathymetry and onshore topography data used for terrain corrections to create seamless land-sea gravity models.
• Analyze station spacing, which varies from 11 km to less than 1 km, to assess data resolution for regional vs. local geological studies.
• Combine ground observations from the Australian National Gravity Database with airborne survey line data totaling 451,000 line km for comprehensive coverage.

Strengths

• Integrates nearly 1.4 million gravity stations from a national database.
• Includes over 450,000 line kilometers of airborne gravity and gradiometry data.
• Provides continent-wide coverage at a cell resolution of approximately 435 meters.
• Compiles data from multiple sources collected over an 80-year period.

Limitations

• Station density is uneven, with spacing varying from 11 km to less than 1 km across the continent.
• The grid is a derived product (half vertical derivative) and not the primary gravity measurements.
• The underlying ground data spans many decades, potentially introducing methodological inconsistencies over time.

Provenance

Source

Geoscience Australia, Australian National Gravity Database, Scripps Institution of Oceanography, NOAA, NGA.

Collection Method

Ground and airborne gravity surveys processed via standard methods and FFT transformation.

Time Range

1940s to 2019.

Freshness

Based on data current as of September 2019, though metadata was updated in 2026.

Geography

Australia and its continental margins.