Over the last three years, a comprehensive subsurface investigation that combines both conventional and geophysical techniques has been conducted near Springfield in southwest Missouri, United States. This study, which forms part of the comprehensive subsurface investigation, aimed to (1) image and characterize the subsurface, (2) map variations in engineering properties of soil/rock, (3) map variable depth to top of rock, (4) explore the utility of the geophysical techniques, (5) determine the factors contributing to karst processes, and (6) propose karst mitigation. Electrical resistivity tomography (ERT) and multichannel analysis of surface waves (MASW) were employed for the acquisition of subsurface geophysical data. Borehole controls were used to verify and constrain the geophysical interpretation.

In some instances, the ERT and MASW techniques produced complementary, high quality, and reliable data consistent with borehole control. Bedrock was pervasively fractured and extensively weathered with pronounced uneven surface. The topography of the surface was observed to depict the topography of the karst bedrock in many of the investigative areas. Moisture content was the major parameter influencing resistivity of the subsurface. A pervasive and systematic network of discontinuities characterizing the bedrock could serve as conduits for percolating acidic waters, ultimately resulting in distinct karst features. Anthropogenic activities were observed as a major contributor to the karst processes. Minimizing the amounts and rate of percolating acidic waters can significantly reduce karst processes and mitigate related features.