Sander Geophysics Limited (SGL) conducted a fixed-wing high-resolution aeromagnetic, gammaray spectrometry and frequency-domain electromagnetic survey in the western part of the Republic of Ireland for the Geological Survey of Ireland (GSI) in the area around Galway incorporating most of County Galway and the south part of County Mayo. The survey block “A2” is part of the ongoing Tellus Programme that commenced with the Tellus Airborne Geophysical survey of Northern Ireland in 2005/2006, conducted by the British Geological Survey (BGS), and the subsequent Tellus Border Survey in 2012 jointly administered by the GSI and the Geological Survey of Northern Ireland (GSNI). The A2 Block survey is adjacent to and slightly overlaps the A1 Block survey that was flown in the vicinity of Dublin in 2015.

 

The survey was conducted using SGL's De Havilland DHC-6 Twin Otter, registration C-GSGF. Production flights commenced on June 2, 2016 and were completed on October 13, 2016. A total of 115 flights were flown during the survey to complete the planned 43,141 line kilometres. The survey operations were conducted from Weston (EIWT), Shannon (EINN) and Galway (EICM) airports.

 

The traverse lines were oriented N15°W and spaced at 200 m. The control lines were oriented E15°N and spaced at 2,000 m. The target clearance was 60 m above ground level, based on the Irish Aviation Authority (IAA) permit. The target average ground speed was 60 m/s, or 115 knots.