Memphis sits on the deep sediment-filled trough of the Mississippi Embayment, where loose sands and thick alluvium amplify seismic waves in ways that bedrock-based codes miss entirely. The 1811–1812 New Madrid earthquakes are a constant reminder that ground motion here can be severe even at distance. In our track record, a simple SPT-based site class often underestimates the hazard. The MASW technique gives you a direct, non-invasive Vs30 measurement that feeds straight into the ASCE 7 site classification. When the profile shows a soft clay cap over dense sand, we sometimes pair it with seismic refraction to map the top-of-bedrock depth across the site, especially near the Wolf River floodplain where channel deposits vary over tens of feet.
In the Mississippi Embayment, Vs30 alone does not tell the full story—basin depth effects can amplify long-period motion that standard site factors miss.
