Akron’s growth from canal town to rubber capital left a patchwork of industrial fill, glacial till, and buried valleys that make seismic site class anything but uniform. When a new structure goes up on East Market or a school addition breaks ground near the Merriman Valley, the building department wants a VS30 number—and they want it backed by field data, not a default assumption. We run active-source MASW surveys across Summit County to measure shear wave velocity in the upper 30 meters, tying results directly to IBC and ASCE 7 site classes. For sites where fill thickness is uncertain, we often pair the surface wave data with SPT drilling to ground-truth the velocity profile against blow counts and soil descriptions from the same borehole.
VS30 in Akron can shift from site class C to D within a hundred feet when the glacial till thins over a buried valley—surface geology maps won’t catch that.
Process overview
Local context
We roll out a 115-foot land streamer with 24 geophones spaced at 5-foot intervals, laying it right on the asphalt or compacted subgrade. The spread connects to a 24-bit seismograph that samples at 0.25 milliseconds—fast enough to catch the high-frequency surface waves that control the top 5 to 10 meters of the velocity profile. On a typical Akron lot, we shoot three to five spreads, overlapping them to build a continuous profile from the building pad to the property line. The biggest practical headache is vibration noise. If a freight train is rumbling through the Akron Northside station a quarter mile away, the low-frequency ground roll contaminates the passive portion of the record and we have to wait out the quiet window. We schedule surveys early morning or late evening for that reason, and we always check the CSX schedule before confirming a site visit near the tracks.
Reference standards
ASTM D4428 / D7400 – Crosshole and surface wave seismic testing, IBC 2024 Section 1613 – Earthquake loads and site class determination, ASCE 7-22 Chapter 20 – Site classification procedure, NEHRP Recommended Provisions – VS30 averaging and site coefficients
Additional services
Standard VS30 Site Classification
Active-source MASW with one to five spreads, 1D VS profile, and NEHRP site class letter for building permit submittal. Typical for single-lot commercial pads and residential additions.
Deep Profile with Passive-Source Extension
Combined active and passive recording using linear and circular arrays. Needed when bedrock is deeper than 100 feet or when the geotechnical engineer requires velocity data to 100 feet for liquefaction assessment.
2D Shear Wave Velocity Cross-Section
Multiple parallel MASW lines gridded across the site, processed into a 2D VS section. Useful for larger developments where lateral variability in fill or buried channels affects the foundation design.
Typical parameters
Quick answers
How much does a MASW / VS30 survey cost for a typical Akron commercial lot?
For a standard single-family or small commercial lot in Summit County, a basic MASW survey with one or two spreads typically runs between US$1,820 and US$2,810. The exact figure depends on access conditions, the number of spreads needed to cover the building footprint, and whether passive-source recording is required to reach the full 100-foot depth. We can usually give you a firm number with a quick look at the site address and a county soil map overlay.
Does the City of Akron Building Department accept MASW for seismic site classification?
Yes. The Akron Building Department follows the Ohio Building Code, which adopts IBC Chapter 16 for seismic design. An MASW survey that reports VS30 and the corresponding NEHRP site class, signed by a qualified geophysicist, meets the site classification requirements under ASCE 7-22. We include the raw dispersion curves and the inversion parameters in the report so the plan reviewer can see exactly how the VS30 number was derived.
How is VS30 different from a standard soil boring, and do I need both?
A soil boring gives you soil type, blow counts, and sample recovery at discrete depths—critical for bearing capacity and settlement. MASW gives you a continuous low-strain shear wave velocity profile that the structural engineer plugs directly into the seismic base shear equation. They measure different things, and on most Akron projects the building department wants both: borings for geotechnical parameters and MASW for the site class letter. We coordinate the two so the velocity profile is calibrated against the boring log at the same location.