Mapping the underground

Gravity sensing

Researchers are developing the next generation of gravity sensors capable of detecting deep-underground hazards such as sinkholes, mineshafts and landslides faster and more precisely. This means potential catastrophes can be spotted earlier and averted.

What lies beneath the ground, and why do we need to know?

Unknown underground conditions present the largest single risk in infrastructure projects and cause significant delays and cost overruns, potentially costing up to half a percent of the gross domestic product of the country, and gravity sensors promise to detect problems before the start of construction. Understanding what lies beneath the ground would also help to protect the existing infrastructure and necessitate fewer, less invasive roadworks. If a rail track can be surveyed weekly, landslips could be spotted before it is too late.

Gravity sensing technology allows sensors to penetrate much deeper below ground than current remote sensing tools are able to do and to make faster measurements of gravity. It opens the possibility of transforming huge sectors and industries, economically and from a health and safety point of view. Gravity sensors will also make a huge difference to everyday life – it will mean clearer roads, due to roadwork interventions, rapid broadband and mobile connections, and even more precise and accurate measurements of droughts, floods and ocean current levels. Other impacted applications include oil exploration, autonomous shipping, water resource management from space, and agriculture.

Gravity sensor development will also mean tackling problems such as developing sinkholes, which can be detected before it becomes critical, so that work can be done to stop it getting bigger and collapsing.

The majority of sensing techniques are limited in their ability to detect targets at depth, and are strongly influenced by ground conditions such as intervening media or weather, but quantum gravity sensing will be used to accurately assess deep targets and will provide an additional data steam for increased confidence.

Underground tunnel detection

In 2021, researchers used gravity gradient sensing technology to find a tunnel buried outdoors one metre below the ground surface. This achievement marked a long-awaited milestone with profound implications for industry, human knowledge and national security.

Hub researchers reported their achievement – a world first for a quantum gravity gradiometer outside of laboratory conditions – in Nature.

Successful sensor validation at sea

In 2023, researchers successfully our gravity gradient sensing technology in trials on a ship in the North Sea in conjunction with university spin-out Delta-g. The technology could offer new capabilities for mapping the ocean and resilient long-term navigation.