High-resolution Seismic Reflection to Identify Areas with Subsidence Potential beneath U.s. 50 Highway in Eastern Reno County, Kansas

High-resolution seismic reflections were used to map the upper 200 m along an approximately 22 km stretch of U.S. 50 highway in Reno County, Kansas, where natural and anthropogenic salt dissolution is known to threaten ground stability. Surface subsidence in this part of Kansas can range from gradual (an inch per year) to catastrophic (tens of feet per second), representing a significant risk to public safety. Primary objectives of this study were to delineate the Permian Hutchinson Salt layer beneath the proposed alignment of the new U.S. 50 bypass around the City of Hutchinson. Of secondary interest were any features with subsidence potential beneath U.S. 50 east of the City of Hutchinson in Reno County, a distance of around 15 km crossing the dissolution front of the salt beds. The high signalto-noise ratio and resolution of these seismic reflection data allowed detection, delineation, and evaluation of several abnormalities in the rock salt layer and overlying Permian sediments. Locations were identified where failure and associated episodes of material collapse into voids left after periodic and localized leaching of the 125 m deep, 40 m thick Permian Hutchinson Salt member were evident. Anomalies were identified within the salt and overlying rock layers with seismic characteristics consistent with collapse structures. Of particular interest were features with the potential to migrate to the surface in areas where no subsidence has been previously observed. Anhydrite and shale layers several meters thick within the salt are uniquely distinguishable and appear continuous for distances of several kilometers. High noise levels from the heavy traffic load carried on U.S. 50 and maintaining continuous subsurface coverage beneath the Arkansas River presented significant challenges to both the acquisition and processing of these data. Over a dozen unique features potentially related to subsidence risk were identified.