Visualization of a GIS-Based Geological and Geotechnical Information for the St. Louis Metropolitan Area, Missouri and Illinois

The St. Louis metropolitan area (STL) is the focus the U.S. Geological Survey's Earthquake Hazard Program's plan for assessing and reducing the risks of an earthquake likely emanating from New Madrid Seismic Zone (NMSZ), which is the most active seismic zone in the Midwestern United States. The STL consists of three counties in Missouri and four in Illinois, which are divided by the state boundary along the Mississippi River. Both of the state's respective geological surveys have produced their own geologic maps and datasets, employing dissimilar geodata information and systems, with differing map units, map scales, and storage formats, with data stored in analog or digital formats. This work combined dissimilar geodata from both states and integrated them into a single Virtual Geotechnical Database (VGDB) in an accepted Geographic Information System (ArcGIS), which can be used to retrieve subsurface data and perform an array of spatial analyses. The VGDB will be made available to the general public and other researchers, and is intended to promote more standardization of geologic interpretations between Missouri and Illinois. The existing body of data was manipulated to extract useful information on the surficial geology, loess thickness, bedrock geology, well locations, and measured values of shear wave velocity in the STL, which were integrated into a GIS ‘information layer'. Depths-to-bedrock basement and groundwater table elevations underling the study area were interpolated using geostatistical methods of ordinary kriging and cokriging, respectively.