The limestone bedrock beneath Cork City conceals a legacy of karstification that standard borehole investigations often miss. The dissolution of the Waulsortian limestone formation, accelerated by the acidic groundwater of the River Lee valley, creates subsurface voids and pinnacled rockhead profiles that vary dramatically over distances of just a few metres. When we deploy seismic tomography lines across a site in the Marina or docklands area, we are not only mapping the overburden-bedrock interface but also imaging the velocity contrasts that indicate weathered zones, cavities, or collapse features. This geophysical approach delivers a continuous cross-section of P-wave and S-wave velocities, which our processing team converts into engineering parameters—rippability, shear modulus, and Poisson's ratio—directly applicable to foundation design under Eurocode 7 (EN 1997-1:2004) and the Irish National Annex. For projects on the glacial tills and alluvial deposits that dominate the city centre, the combination of refraction for shallow layering and reflection for deeper structure is particularly effective. We integrate these results with invasive testing programs, and for sites where karst risk is identified, we often recommend supplementary MASW surveys to characterize the shear-wave velocity profile to 30 metres for site classification per EN 1998-1.
A 2D seismic velocity model can reveal a limestone pinnacle or void that a 5-metre grid of boreholes would completely miss—this is the value of continuous imaging.
