Gloucester sits on the Lias clay at the foot of the Cotswolds. The Severn Vale soft alluvium amplifies ground motion in ways a standard desk study misses. We run seismic microzonation fieldwork that maps shear wave velocity profiles across the site. This is not a generic hazard map pulled from a database. We drill, we log, and we correlate the stratigraphy with downhole geophysics. The output is a grid of site-specific response spectra you can hand straight to the structural engineer. For deep clay sites near the docks, we often pair this with a CPT test to catch thin peat layers that skew the Vs profile. BS EN 1997-1 tells you to consider ground conditions. Our microzonation work tells you how the ground will actually shake.
A site in central Gloucester can have three different response spectra across 100 metres. Microzonation finds those boundaries before you pour concrete.
