Paleoseismic Investigation of the Meadow Bank Lineament in the Wabash Valley Seismic Zone: Collaborative research between the University of Illinois and the University of Kentucky

The Meadow Bank Lineament (MBL) is a remarkably straight 5 to 10 m high escarpment in the lower Wabash Valley Seismic Zone, located in east-central White County, Illinois. The MBL and related features are about 1.5 km east of and closely parallel to the trace of the Herald-Phillipstown Fault Zone (HPFZ), mapped on the Pennsylvanian age West Franklin Limestone Member of the Modesto Formation. The close parallelism of the MBL and the HPFZ raises important questions: Is this surficial feature genetically related to the HPFZ or some parallel, but unknown fault? Does this feature represent surficial expression of recent reactivation along preexisting faults? Or is this simply a recent erosional feature? If it is an erosional feature, does the parallelism to the HPFZ indicate that the erosional pattern was controlled by preexisting structural features? If this surficial feature is of a tectonic origin genetically related to the HPFZ, it will pose a threat to the area. In this case, it is directly relevant to the earthquake hazard reduction program and warrants more investigation. Our investigation will utilize a multi-disciplinary approach to determine whether the MBL is the result of Quaternary faults or erosional forces of the Wabash River. We propose to integrate high resolution geophysics, along with Quaternary and geomorphic mapping, and an analysis of newly released coal elevation data from the underlying Pattiki coal mine, in a comprehensive investigation of the MBLMBL. We will combine tools and expertise available from the Kentucky Geological Survey (KGS) and the Illinois State Geological Survey (ISGS). Our objectives are to first geophysically image the Quaternary and Pennsylvanian sediments on either side of the MBL (ISGS) to determine whether any of them appear to have been offset by Quaternary faulting. We will examine related features within the Wabash River floodplain to determine the erosional history of the study area and to search for other evidence of past seismic activity (ISGS and KGS). We will use the geophysical data to direct and inform test drilling (KGS shallow, ISGS deep), coring and finally, trenching (KGS). Carbon and Optically Stimulated Luminescence dating methods will be used to document the age of offsets in sediments. We anticipate that this project may conclusively demonstrate Quaternary faulting along the MBL within the Wabash Valley Seismic Zone in southern Illinois. Although similar faulting has been demonstrated farther south, this would be the first instance of fully documented Quaternary faulting this far north. This proposal directly addresses several of the NEHRP priorities for the central United States. This is a paleoseismologic investigation of a potential Quaternary fault with a surface expression in the Wabash Valley Seismic Zone. This potential fault lies 40 km west of Evansville, Ind., the focus of a new USGS urban seismic-hazard mapping project. Several large industrial plants and major components of the region’s infrastructure lie within a 50-km radius of the potential fault. If the lineament is confirmed to be an expression of the fault, results from this project would help to better define the threat this fault poses to these communities, industries, and their infrastructure, and will allow them to make more accurate plans and mitigation strategies to reduce losses stemming from future seismic activity.