The Tellus programme, operated by Geological Survey Ireland, is a national programme gathering
geochemical and airborne geophysical data across Ireland. As part of the geophysics programme, time-
domain electromagnetic (TDEM) data were measured in one survey block in 2014 and frequency-domain
electromagnetic (FDEM) data have been acquired in other data blocks since 2011 (Figure 1). The subsurface
resolution capabilities of both datasets are currently poorly understood. Project RAFTA will examine the
resolution capabilities of both the frequency-domain and time-domain data and will consider all aspects of
the data, including flight height, system noise and anthropogenic noise, which affect the resolution. The
resistivity models and model resolutions derived from recorded data will be tested against other constraints
where available that will include borehole logs, wireline resistivity logs and ERT sections, where possible at
test locations of interest in groundwater, bedrock mapping and Quaternary mapping. Model resolution will
also be assessed using synthetic data examples for a wide range of subsurface geological structures. The
maximum depth of investigation provided by these data are well suited for investigation of, e.g., overburden
thickness; nature of overburden material, including Quaternary deposits; depth to bedrock; bedrock
lithology
