The Shannon Estuary’s deep alluvial clays and the Carboniferous limestone bedrock beneath Limerick create a sharp impedance contrast that amplifies seismic waves, even from distant offshore events. The city sits on a variable subsurface: stiff glacial till overlying karstified limestone in parts of the south side, while the docklands and floodplain near the Abbey River rest on 15 to 30 metres of soft estuarine silts. A uniform 0.7 m/s² PGA reference value means little without site-specific data. We run downhole shear-wave velocity surveys and MASW profiles to map VS30 across the site, feeding directly into EC8 ground-type classification. For projects near the river corridor, we often pair this with liquefaction screening, as the loose saturated silts at 4–8 m depth show cyclic resistance ratios that demand careful evaluation under the 475-year return period.
VS30 measured at 210 m/s reclassified a Limerick quayside site from Eurocode 8 Class E to Class C, cutting the design seismic coefficient by nearly 30%.
