by Duygu kiyan & giuseppe Maggio, DIAS

Exploring the Earth beneath County Antrim

with the GEMINI Passive Seismic Array

24 April 2025

Having joined the GEMINI project at Dublin Institute for Advanced Studies (DIAS) in October 2024, Giuseppe Maggio immediately started scouting and permitting for seismic station installation in Co. Antrim, Northern Ireland.

In January, Giuseppe, along with Colin Hogg (Senior Technician at DIAS) and members of the Geological Survey of Northern Ireland, then began installing the passive seismic stations. These stations will record data for the next 18 months to capture naturally occurring ground vibrations — from distant ocean tides to local human activities such as traffic and industrial operations; from natural events like storms to minor and distant earthquakes. The seismic vibrations move at different speeds through rock layers of different density and temperature and reach the passive seismic stations at different times. The wave data can then be processed by scientists to image the subsurface.

The data collected from seismic stations across County Antrim will be analysed to give us a better understanding of the layers of rock beneath our feet — all the way down to 5 km below the Earth’s surface.

Did you know?

A teleseismic earthquake is a tremor caused by an earthquake that originates more than 1,000 km away from the recording station.

How do we collect the data? Keeping our sensors safe from water is crucial, so the team came up with a clever way to protect the electronics. Here is how it works: First, we dig a hole about 50–80 cm deep and 30 cm wide. We pour some concrete in the bottom to give it a solid base. Then, we place a plastic drum down into the concrete and fill the bottom of the drum with cement to make a nice, flat floor for the seismic sensor to sit on. Once the cement has dried, we carefully place the sensor inside, making sure it is perfectly level and pointing North — this helps us figure out which direction the seismic waves are coming from. After that, we hook up all the cables and seal everything up safely inside the drum. The cables run out to a connection box, which links the sensor to its power source — a solar panel (1.2 m by 0.8 m) and battery (12 Volt) setup — so it can keep working out in the field without a problem.

So far we have deployed 22 stations, 4 stations to go!

What does the data look like? The plots in the image show seismic data recorded by our station ANT21 during Storm Éowyn. The first plot displays how ground motion changed over time, revealing the storm’s seismic signature. The second plot, called a spectrogram, shows the frequencies of these signals — helping us see how the storm’s energy was distributed over time at different frequencies, as captured by ANT21. We can also see other signals created by nearby traffic, which highlights how seismometers not only detect natural events like storms but also everyday human activity, offering a unique look into the vibrations around us.

Giuseppe and I will be doing regular check-ups and data downloads from each seismometer about every 2 to 3 months to keep everything running smoothly. If you happen to spot us out in the field while we are installing or servicing the instruments (don’t worry — we always have the landowner's permission), feel free to come say ‘Hi’ and ask us about the project!

Images: After a sunny day out in the field, Giuseppe and Colin wrapped up the installations at two different stations. The setup is looking solid — with the waterproof black box keeping our batteries and cables safe and dry (Photo: Giuseppe Maggio); Seismic data from station ANT21 reveals ground movement caused by Storm Éowyn.

DIAS is a GEMINI partner.