Gravity surveys are a well-established geophysical technique used to investigate variations in the Earth’s subsurface. By detecting subtle changes in the strength of the gravitational field, they reveal contrasts in rock density that correspond to geological structures, mineral deposits, or even buried archaeological remains.
Different gravity survey methods are suited to Individual project types, terrain conditions, and scales of investigation. Below, we outline the main approaches used in practice, together with their benefits, limitations, and applications. If you would like to know more about the different types of gravity survey methods, or if you have an application, please contact our team today.
Airborne gravity surveys are among the most efficient ways to acquire data across large and often inaccessible areas. Gravimeters are mounted inside fixed or rotary wing aircraft, with GPS and inertial navigation systems correcting for aircraft movement. This allows rapid, regional-scale coverage where ground access is difficult or impossible.
At Metatek, airborne surveys are a particular speciality. Our flagship platform is a Douglas DC3T, a purpose-built survey aircraft with exceptional endurance and stability. With an eight-hour operational range, short take-off and landing (STOL) capability for remote airstrips, and a 100-foot wingspan for smoother flight, the DC3T is uniquely suited to survey campaigns in challenging environments. It has upgraded avionics, five-bladed propellers, and over-wing exhaust systems that reduce acoustic output, ensuring both safe and quiet operations.
Equally important, the aircraft has been fully modified to remove magnetic effects, producing a “magnetically quiet” platform that maximises the quality of data collected. Surveys are flown by our highly experienced pilots, several of whom have over 15,000 flight hours and extensive experience operating across five continents. For all projects, Metatek deploys twin-engine aircraft to ensure safety without compromising on data integrity.
Advantages: Rapid acquisition across vast areas; effective over dense forests, mountainous terrain, and remote regions.
Limitations: Resolution is lower than ground-based surveys; extensive data processing is required to remove aircraft motion effects.
Applications: Regional geological mapping, frontier mineral and hydrocarbon, transition gas and geothermal exploration, and environmental projects requiring broad coverage.
Ground-based gravity surveys are the most traditional and direct approach. Using portable gravimeters, field teams take measurements across a planned grid or along seismic survey lines. This method provides detailed coverage of specific sites and higher-resolution datasets than airborne surveys.
Metatek deploys ground gravity surveys when projects demand precision at a local scale. Examples include:
Advantages: High accuracy; adaptable to small or medium-sized sites.
Limitations: Time-intensive; requires physical access to each survey location.
Applications: Targeted exploration, construction feasibility studies, heritage site investigations.
Gravity surveying is not confined to land or air, however. By mounting gravimeters on vessels or towed platforms, marine gravity surveys extend coverage into offshore environments. GPS and stabilisation systems are used to correct for ship movement, ensuring data reliability even in variable sea states.
For industries and research programmes working offshore, marine gravity surveys provide critical context. They can reveal the structure of continental shelves, locate potential hydrocarbon reservoirs, and support seabed mapping for both scientific and commercial purposes.
Advantages: Effective coverage of large offshore areas; provides data that complements seismic surveys.
Limitations: Resolution is affected by sea conditions
Applications: Offshore oil and gas exploration, marine geology, and environmental studies.
Gravity gradiometry measures the spatial rate of change in the gravitational field rather than the field itself. This is achieved by comparing accelerations between two or more points within the same instrument.
Advantages: High sensitivity to small-scale features; improved resolution for shallow or subtle anomalies.
Limitations: Complex, expensive instrumentation; requires specialised interpretation.
Applications: Mineral, hydrocarbon, transition gas and geothermal prospecting, detailed structural mapping, archaeological detection of buried walls or voids, and defence applications.
Airborne gravity gradiometry has become an important tool in frontier exploration, offering higher resolution than standard airborne gravity surveys.
The choice of survey method depends on several factors:
Scale: Ground surveys offer fine detail; airborne and marine surveys provide regional coverage; satellites deliver global context.
Resolution: Gradiometry and ground surveys achieve the highest resolution; airborne and satellite methods trade detail for area.
Logistics: Terrain accessibility, budget, and project timescales all influence the selection.
Often, multiple methods are combined. For example, airborne gravity may outline regional structures, while targeted ground surveys refine specific anomalies.
Collecting gravity data is only the first step. Raw measurements must be carefully processed to correct for influences such as latitude, elevation, and instrument drift. This ensures that the final dataset reflects only the geological variations of interest.
At Metatek, we provide not only the survey itself but also complete data processing and interpretation services. By integrating gravity results with other geophysical datasets — such as magnetics or seismic — we build coherent geological models that support informed decision-making. Expert interpretation is essential, as a single gravity anomaly can have multiple possible causes. Our team ensures results are placed in their correct geological context, maximising value for clients across exploration, archaeology, and conservation.
From handheld gravimeters on archaeological sites to satellites monitoring global ice loss, gravity survey methods span a wide range of scales and applications. Each technique has distinct strengths and limitations, but all share the principle of mapping density contrasts through variations in the Earth’s gravitational field.
For projects in geology, archaeology, conservation, and resource exploration, gravity surveys remain a fundamental geophysical tool.
Metatek provides complete survey and data processing services across multiple geophysical techniques, including airborne gravity. To find out how these methods could support your project, please contact our team.
