Australian National Gravity Anomaly Grid with Tilt Filter

Nearly 1.8 million gravity observations, including 1.4 million ground stations and over 450,000 line kilometers of airborne surveys, were compiled to create this continental-scale grid. The Australian government's Geoscience Australia processed and quality-checked the data, which integrates measurements from the 1940s to 2019. This 2019 compilation applies a de-trended global isostatic residual (DGIR) tilt filter to highlight geological structure edges.

Use Cases

• Mapping subsurface geological unit edges using the DGIR tilt filter grid values.
• Integrating the 435-meter cell size gravity grid with magnetic or seismic datasets for joint geophysical interpretation.
• Analyzing long-term changes in Earth's crust by comparing this 2019 grid with future national compilations.
• Calibrating regional gravity models using the included near-field and far-field isostatic corrections.

Strengths

• Integrates approximately 1.8 million gravity observations from multiple sources.
• Combines 1.4 million ground stations with 345,000 line km of airborne gravity and 106,000 line km of airborne gravity gradiometry data.
• Provides a consistent continental grid at a 0.00417-degree (approximately 435m) cell resolution.
• Data quality was verified by Geoscience Australia geophysicists to be fit-for-purpose.

Limitations

• Ground station spacing is irregular, varying from 11 km to less than 1 km across the continent.
• The grid is a processed derivative; raw observation data and specific measurement uncertainties are not included.
• Temporal coverage is broad (1940s-2019), potentially introducing consistency issues between early and modern surveys.

Provenance

Source

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

Collection Method

Processed from ground observations, airborne gravity/gradiometry surveys, and global gravity grids using de-trending and Fast Fourier Transform (FFT) filtering.

Time Range

1940s to 2019

Freshness

The underlying observation data is current as of September 2019; the grid was published in 2026.

Geography

Australia and its continental margins