Eurocode 8 (EN 1998-1:2004) mandates a ground type classification for every new structure in Ireland, and Celbridge's variable geology makes the MASW method the most practical way to get it right. The town sits on the Lucan Formation—a mix of dark limestone, shale, and overlying glacial till deposited during the last ice age. That till blanket varies from two metres to over ten across short distances, so a single borehole rarely captures the full picture. An active-surface-wave survey lines up 24 geophones, records Rayleigh wave dispersion, and inverts the data to produce a continuous shear wave velocity profile down to 30 metres. The result is Vs30, the time-averaged shear wave velocity the code needs to assign Ground Type B, C, or D. For Celbridge's expanding residential zones around the Liffey valley, getting that classification wrong means redesigning foundations months later. When we pair MASW with a few SPT boreholes on the same site, the correlation between penetration resistance and Vs gives the design team a confidence level no desk-study can match.
A Vs30 value from one borehole in glacial till can mislead the entire seismic design category—MASW averages the ground truth across the whole footprint.
