MICROGRAVITY

What is Microgravity?

Microgravity is a geophysical method that measures minor changes in the force of the Earth’s gravity. Thanks to modern equipment and careful field procedures, we can now measure gravity changes as small as 1 part in 1,000,000,000.

How it works

Changes in gravity measured at the earth's surface reflect the underlying geological structure; hence the accurate determination of gravity leads to an understanding of the ground beneath. Through this geophysical method, we can detect and map shallow and localized geologic anomalies such as bedrock channels, fractures and cavities. Man-made anomalies can also be identified.

The presence of differing sub-surface materials results in changes in densities, the most extreme case being voids or cavities. These changes in density result in extremely small anomalies in measurements of the Earth’s gravitational field.

The incredible accuracy of the state-of-the-art equipment used combined with intensive data processing means that these very small deviations can be used to detect both natural and man-made structures.

When the gravity meter is directly over a dense material, such as a concrete slab, a higher reading will be recorded. When over a low density feature, such as a void, a lower reading will be recorded.

The size of the anomaly will depend mainly on the size, depth, shape and orientation of the feature.

The graph shows a microgravity survey over a brown field site prior to a new shopping development including an underground car park. The records suggest the presence of an old mineshaft on site spotted by a low anomaly. Higher gravity readings also indicated the presence of unexpected concrete foundations below ground.

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