COMPARISON OF GEOPHYSICAL AND STATISTICAL ESTIMATES OF SURFICIAL MATERIAL THICKNESS AT SELECTED SITES WITHIN THE COVENTRY QUADRANGLE, COVENTRY, CONNECTICUT

Surface geophysical methods were used to estimate the thickness of unconsolidated sediments at selected locations within the Coventry Quadrangle in Coventry, Connecticut. The geophysical surveys were conducted to evaluate mapped estimates of sediment material thickness generated from a statistical analysis of domestic well completion reports, geologic maps, and aerial topographic surveys using light detection and ranging (LIDAR) elevation data.

The geophysical surveys included active-source [refraction and multi-channel analysis of surface-wave (MASW)] and ambient-noise [horizontal-to-vertical spectral ratio (HVSR)] seismic techniques. Five surface geophysical survey locations were selected to include a range of surficial materials, expected depth to bedrock, and density of ground-truth information (e.g., outcrops and wells).

Comparison of the geophysical results with the statistical mapping indicates the agreement between the seismically and statistically derived estimates of surficial material thickness depends on the density of ground-truth information. Whereas there is fair agreement between results from the geophysical and statistical approaches in the vicinity of wells, comparison of estimates from the seismic techniques to those from the statistical analysis degrades as the distance to the nearest well increases.