Portlaoise sits on a subtle drumlin landscape where glacial till overlies limestone bedrock, creating abrupt lateral changes in stiffness that seismic refraction alone often misses. The damp Irish midlands climate keeps the shallow water table high year-round, softening the upper layers and altering the effective stress regime. A MASW survey cuts through this ambiguity, delivering a continuous VS30 profile that ties directly to Eurocode 8 ground type classification. The non-dispersive nature of the limestone at depth and the variable thickness of overburden make surface-wave methods particularly efficient here compared to invasive borehole techniques. When planning any structure requiring seismic design verification, the seismic microzonation framework benefits directly from the shear wave velocity data we collect across Portlaoise and the wider Laois region.
Surface-wave dispersion inversion provides a VS30 value in under two hours on a Portlaoise greenfield site, without a single borehole.
