Dublin Seismic Survey Project

Exploring for geothermal energy deep beneath our capital city

The Dublin Seismic Survey is a new initiative that aims to build a clearer picture of the geology deep beneath Dublin and improve our understanding of the city’s geothermal energy potential.

By collecting high-quality geophysical data using non-invasive methods, Geological Survey Ireland, a part of the Department of Climate, Energy and the Environment, will image geological structures and investigate potential geothermal targets approximately 2–3 kilometres beneath the city.

This seismic reflection survey will build upon previous research to reduce uncertainty and support future geothermal exploration. All data from the survey will be publicly available and will help to inform future development of secure, local and renewable geothermal energy in Ireland.

The Dublin Seismic Survey project will run until September 2027. A request for tenders from experienced contractors has been published, and the survey is expected to take place in early 2027. The final route for the survey will be published in late 2026. Up to date information will be made available throughout the project on the Geological Survey Ireland website (www.gsi.ie) and specific queries can be emailed to geothermal@gsi.ie.

Investigating our geothermal resources

Geothermal energy is energy stored in the form of heat beneath the surface of solid Earth. It can be stored heat from the Sun, or heat from the interior of our planet. It is renewable, secure, reliable, and local. It is a commercially proven form of energy that can be used for heating and cooling buildings and generating electricity.

Shallow geothermal heat pumps are a scalable technology that is already used in Ireland. Over 20,000 geothermal heat pump systems are in use in Ireland including commercial-scale systems.

Deep geothermal energy can also play a significant role in Ireland’s transition to a carbon neutral and circular economy. Recent research has shown that Ireland has significant untapped deep geothermal resources that could be used for large heating projects such as district heating networks. Investigative projects such as the Dublin Seismic Survey will help to close knowledge gaps about our deep geology and reduce uncertainty for future geothermal projects.

The Department of Climate, Energy and the Environment is taking steps to address the barriers to the uptake of clean, secure and renewable geothermal energy. The Policy Statement on Geothermal Energy for a Circular Economy (DCEE, 2023) sets out a roadmap to delivery of legislation and regulation for the nascent geothermal sector in Ireland.

What is seismic reflection surveying?

Seismic reflection is a well-established geophysical technique used to investigate geological structures beneath the Earth's surface.

During the survey, a specialised vehicle will generate controlled vibrations at selected locations along a predetermined survey route through the city. These vibrations will create seismic waves that travel down through the ground.

When the seismic waves encounter different geological layers and structures, some of their energy will be reflected back towards the surface. These returning signals will be recorded by sensitive instruments positioned along the survey route.

By processing thousands of these measurements together, geoscientists can create an image of the geology beneath the survey area.

The individual measurements, or vibration “sweeps”, can last for one or two minutes at each location. The vibroseis truck then moves on to the next location.

How a Seismic Reflection Survey Works:

• A specialised truck travels slowly along selected city streets and pauses roughly every 20 metres.
• The truck gently vibrates a metal and rubber plate against the ground to create a controlled soundwave.
• This soundwave travels underground, reflects off geological layers, and returns to the subsurface.
• Small, unobtrusive seismic receivers placed along the route record these returning signals.
• The collected data is processed to create an image of the deep rock layers beneath Dublin
• This technique is safe, non-invasive, and comparable in noise to standard heavy goods vehicles. Similar urban surveys have been completed successfully for geothermal energy in the United Kingdom, France, Denmark, Germany, Poland, Switzerland, and the Netherlands.

What will the survey show us?

The Dublin Seismic Survey is needed to give geoscientists a much clearer picture of the geology beneath the city, and the deep geothermal energy potential.

The survey alone will not determine whether a commercially viable deep geothermal resource exists beneath Dublin. Instead, it is an important evidence-gathering step in assessing deep geothermal potential.

The survey will help us to:

• Increase our understanding of the limestone Dublin Basin.
• Identify potential deep geothermal reservoirs.
• Map geological structures in the rock.
• Support future geothermal development by reducing subsurface uncertainty.
• Improve our knowledge of Ireland’s geology.

What happens after the survey?

The data collected during the survey will undergo specialist processing to transform the recorded seismic signals into images of the subsurface. The data will be used by researchers to enhance existing 3D models of the deep geology beneath Dublin.

To fully understand deep geothermal potential across Ireland, more seismic surveys will need to be conducted. The Dublin Seismic Survey will demonstrate best practice in urban data collection for deep geothermal developments and will help to inform the planning and delivery of similar future surveys elsewhere.