Australian National Gravity Anomaly Grid With First Vertical Derivative

Australia and its continental margins are covered by a gravity anomaly grid with a 435-meter cell resolution. The grid integrates nearly 1.4 million ground stations from the national database and offshore data, compiled by Geoscience Australia and partner organizations. It represents the first vertical derivative of de-trended isostatic residual anomalies, processed from data collected from the 1940s to 2019.

Use Cases

• Map basement rock density contrasts using the first vertical derivative of de-trended global isostatic residual anomalies.
• Delineate sedimentary basin geometry and depth by interpreting gravity anomaly gradients over the continental margin.
• Integrate with magnetic or seismic data using the 435m grid cell size for joint geophysical inversion studies.
• Assess regional isostatic state by analyzing the de-trended global isostatic residual anomaly values across the continent.

Strengths

• Integrates nearly 1.4 million gravity station observations from a national database.
• Provides continent-wide coverage of Australia and its margins with a consistent 435m cell size.
• Data quality was checked by GA geophysicists and uses standardized processing methods.

Limitations

• Ground station spacing is irregular, varying from 11 km to less than 1 km, causing variable local resolution.
• The grid is a derivative product; original raw gravity measurements are not directly provided.
• Offshore data is sourced from a global model (v28.1), which may have lower resolution than the terrestrial data.

Provenance

Source

Australian National Gravity Database (ANGD) and Scripps Institution of Oceanography global grid.

Collection Method

Grid derived from ground and marine gravity observations, processed via FFT to calculate the first vertical derivative.

Time Range

1940s to 2019

Freshness

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

Geography

Australia and its continental margins