Tellus employs a low-flying aircraft to collect geophysical information on the properties of soils, rocks and waters below ground. Flying at 60 m, the aircraft is able to sense geological properties not apparent from conventional mapping techniques, effectively ‘seeing through’ Ireland’s often deep glacial deposits and extensive peat and soil cover. This method of acquisition is the most rapid and cost-effective means of acquiring regional-scale geophysical data for supporting geological mapping, mineral exploration, radon risk mapping and geothermal energy exploration.

After the successful completion of the county Galway in 2016 the airborne survey is due to fly Co. Mayo and Western Donegal from spring till autumn 2017.  This survey follows on from the  successful Eastern Ireland survey, Tellus Border and North Midlands surveys. Results of these surveys are available to view and download free of charge on our data page.

Magnetic Anomoly (nT)

The survey aircraft

The aircraft is a de Havilland DHC-6 Twin Otter plane operated by the specialist survey company, Sander Geophysics Ltd, based in Canada. The white, twin propeller plane has a red tail, black stripe, and registration number C-GSGF.

The aircraft is equipped with three geophysical instruments which measure the magnetism, radioactivity and conductivity of the Earth below. It undertakes measurements as it flies at a speed of approximately 130 mph (approx 216km/h).

The aircraft flies at 60 m (196 ft) above ground level, which is approximately 8 times the height of a two-storey house. Survey lines are flown at a spacing of 200 m. When the aircraft is flying at survey height it’s sound is similar to that of a passing lorry.

Survey Aircraft in Flight

Click our info-graphic for more facts and information

The geophysical data is helping to:

Update geological maps; from soils at the surface to faults and geological structures at hundreds of metres underground.

Improve radon risk maps.

Understand groundwater resources.

All the data collected is freely available once it has been fully checked and processed.

For further information about the geophysical survey, or to be added to the mailing list to receive data release notifications, please email

Further Information

If you are located in the survey area and feel your animals may be affected please contact us on 1800 303 516 or email us at Also you can read our FAQs.