Cambridge's building stock spans over eight centuries, from medieval college foundations resting on Gault Clay to modern laboratories in the West Cambridge site. This layered history directly shapes today's geotechnical requirements. The River Cam's alluvial corridor, with its soft silts and hidden peat lenses, demands subsurface imaging techniques that go beyond isolated boreholes. Seismic tomography provides a continuous two-dimensional velocity section, mapping the interface between made ground, river terrace gravels, and the underlying Gault Formation. For deeper targets, such as the Chalk bedrock at 25 to 40 metres, reflection processing resolves structural discontinuities that affect pile design. The method is particularly relevant where test pits cannot reach sufficient depth and borehole SPT data requires spatial interpolation between investigation points.
Velocity contrasts between Gault Clay and Chalk bedrock are diagnostic for mapping dissolution features that threaten foundation integrity in Cambridge.
