A 24-channel seismograph deploys on a gravel car park off the A33, geophones spiked into the made ground that covers much of Reading. The array stretches 46 metres, enough to capture Rayleigh wave dispersion down to the 30-metre target required by Eurocode 8 for VS30 classification. A sledgehammer strikes an aluminium plate, and the surface waves roll through Reading’s complex Quaternary sequence – river terrace gravels overlying the Lambeth Group clays and sands, then into the chalk bedrock that defines the town’s western edge. Within forty minutes the crew has the raw shot gather and moves to the next spread, building a continuous shear wave velocity profile without a single borehole. For sites where the water table sits high in the Kennet floodplain gravels, the seismic refraction method sometimes complements the survey to map the top-of-chalk refractor.
VS30 classification in Reading can shift by a full site class within 200 metres when crossing from river gravel onto chalk.
Common questions
What does a MASW survey in Reading cost?
For a typical single-line MASW survey producing a VS30 classification, costs in Reading range from £1,160 to £2,120 depending on array length, number of spreads, and site access conditions. Surveys requiring multiple lines, traffic management on public roads, or night working fall at the upper end of the range. Each quotation includes data acquisition, dispersion analysis, inversion modelling, and a factual report with the VS profile and site class assignment per BS EN 1998-1.
How long does a MASW survey take on a typical Reading site?
A single MASW spread with 24 geophones takes 40–60 minutes to set up, acquire, and begin processing. A full-day crew can complete 6–8 spreads on an open site, covering 200–300 metres of linear transect. The final processed VS30 profile and report are delivered within three working days. Sites with heavy vegetation, steep slopes, or hard-standing requiring geophone mounting putty add time to the setup.
Is MASW reliable on the gravelly soils common in Reading?
Yes. The dense river terrace gravels that cap much of Reading generate strong Rayleigh wave dispersion across the 10–30 Hz band, which is ideal for resolving the upper 20–30 metres. The velocity contrast between gravel and the underlying chalk produces a clear dispersion curve inflection that improves inversion stability. On sites where the gravel is thin or patchy, we extend the array length to 69 metres to maintain resolution at depth.
Does MASW replace boreholes for a ground investigation in Reading?
No. MASW provides continuous shear wave velocity profiles but does not recover samples, classify soil, or measure groundwater. It complements boreholes and CPTs by filling the spatial gaps between point investigations. On a typical Reading project, we combine MASW lines with targeted SPT drilling or CPT soundings to calibrate the velocity model against lithology, producing a ground model that satisfies both geotechnical and geophysical requirements under BS 5930.
