Geophysical Surveys | National Oceanography Centre

What is geophysics and why is it important?

Geophysics is the only way we can really see inside the Earth and oceans over large distances. While drilling or sampling gives us valuable information, those approaches are limited to single points. Geophysical surveys are different; they let us build continuous images that stretch for hundreds of kilometres and reach parts of the planet that are otherwise totally inaccessible.

The strength of geophysics is that it works across so many scales. Globally, satellites reveal the planet's gravity and magnetic fields. Regionally and locally, we can image entire ocean basins, continental margins, or volcanic systems. At the smallest scale, we can apply geophysical methods to individual rock samples, ice sheets, or even engineered structures. This flexibility makes geophysics a scientific discipline in its own right, but also a vital tool that supports many other areas of science.

What are the two main approaches in geophysics?

There are two broad approaches:

Passive methods use signals that are generated naturally by the Earth. This includes things like earthquakes, variations in gravity and magnetism, or electrical currents caused by the solar wind interacting with Earth's magnetic field (which is the basis of magnetotellurics). These signals are always available and give us insights into the deep structure of the planet.
Active methods generate signals in a controlled way. For example, we use seismic sources to send sound waves into the Earth and record how they reflect or bend through different layers. We can also apply electromagnetic pulses to probe the electrical properties of rocks and sediments.

What can we study using geophysical surveys?

By combining passive and active methods, geophysics gives us a uniquely powerful toolkit for exploring the ocean and the Earth beneath it. With these techniques, we study tectonic processes, identify geohazards like earthquakes and submarine landslides, assess where marine mineral resources are, and contribute to cleaner energy solutions that support the UK's transition to net zero. At the National Oceanography Centre, we apply geophysical surveys across the entire ocean system, from shallow continental shelves to deep basins, and from polar seas to tectonic plate boundaries, including throughout the water column.

Why is geophysics fundamental to ocean science?

Geophysics is fundamental to ocean science because it studies the very processes that form the ocean basins. By imaging the Earth's deep structures, geophysics shows us how tectonic plates move apart, how new crust is created at ridges, and how continents rift and margins evolve. In other words, it lets us study the processes that literally shape the oceans themselves.

Once formed, oceans continue to interact with the solid Earth and the biosphere. Geophysics gives us the tools to investigate these connections. By monitoring earthquakes, volcanic activity, and submarine landslides, we can assess geohazards that affect coastal communities and ecosystems. By mapping sub-seafloor structures, we can identify where fluids and gases circulate, which links directly to climate change and the release of greenhouse gases like methane.

Geophysics also underpins the sustainable supply of energy and resources. It helps identify marine mineral deposits that are important for renewable energy technologies, and it supports the search for safe storage sites for carbon and other low-carbon energy solutions. In polar regions, geophysical methods can even be used to measure sea ice thickness, providing data that's essential for both climate research and safe navigation.

Without these insights, we would lack a fundamental understanding of how the oceans are created, how they evolve, and how they interact with the wider Earth system.

How does NOC conduct geophysical research?

At the National Oceanography Centre, we combine advanced modelling, world-class facilities, and strong partnerships to carry out geophysical research. Before even going to sea, we design surveys with computer models that show where instruments will provide the most useful information. This ensures that each expedition delivers targeted results.

Our research vessels, operated through the National Marine Facilities, carry specialist systems including:

Seismic equipment to image beneath the seabed
Gravimeters to measure tiny variations in gravity
Magnetometers to record the Earth's magnetic field

Through the UK Ocean Bottom Instrumentation Consortium, we access a wide pool of seafloor instruments, such as broadband and short-period seismometers, controlled-source electromagnetic instruments, and magnetotelluric systems. Together, these facilities give the UK one of the most complete geophysical capabilities in the world.

What innovative technologies is NOC developing?

We are pioneering fibre-optic sensing, transforming existing seafloor cables into thousands of sensors that record vibrations and pressure changes. This breakthrough allows us to monitor earthquakes, ocean circulation, and environmental change over very large areas with high resolution.

Autonomy is a defining strength at NOC. Our tools include:

Ocean bottom nodes deployed and recovered by remotely operated vehicles (ROVs)
A new ROV-mounted seismic source (in development) for high-resolution imaging in deep environments
Autonomous underwater vehicles that carry sensors into remote or ice-covered regions, opening up areas of the ocean never before surveyed

A core strength of NOC is our multi-method approach. We compare geophysical results with findings from physical oceanography, biogeochemistry, and ecology. This means our research always sits within the wider ocean and Earth system. International collaborations also ensure our research remains at the forefront of discovery.

What has NOC's geophysical research revealed?

Our research has improved our understanding of how continents break apart, how magma and fluids move through the crust, and how methane escapes from sediments into the ocean. These insights support assessments of hazards, climate change, and the use of marine resources.

Our work also has practical benefits for society. Geophysical surveys identify slopes that are vulnerable to collapse, improve forecasting of Arctic sea ice, and inform the design of efficient sonar systems for environmental monitoring. Our results are published widely, providing evidence that informs both science and policy.

Sharing Our Research

We share our geophysical work with both the scientific community and the public. NOC researchers present results at international conferences, contribute to news articles, podcasts, and videos, and engage directly with schools and stakeholders. We also use soundings, images, and models to make the invisible structures beneath the oceans accessible to wider audiences.