ST. LOUIS, MISSOURI AREA SURFICIAL MATERIAL DATABASE AND EARTHQUAKE HAZARD MAPPING

PALMER, J.R., MESKO, T., JAMES, K. AND CADORET, J., Missouri Department of Natural Resources, Division of Geology and Land Survey Box 250 Rolla, Missouri 65402-0250, jim.palmer@dnr.mo.gov.

The National Earthquake Hazard Reduction Program has funded our project to compile geotechnical-boring data for the St. Louis, Missouri metropolitan area. We have collected and edited data from the Missouri Department of Transportation and are working with records from the St. Louis Metropolitan Sewer District. The current database has 2385 logs that are in a series of Microsoft Access tables. The tables include records from: 3327 core log entries, 13,602 materials descriptions, 8716 physical properties entries that include 5251 SPT entries, and water levels from 431 borings.

The data has been exported to GIS files for evaluation of the variability between surficial material geologic units and their associated geotechnical properties. Few of the boring logs include either genetic or lithostratigraphic correlations that translate readily to geologic map units because the data was collected for site design and construction purposes rather than stratigraphic analysis and mapping. For example N60 SPT values for CL and CL-ML soils vary from 2.4 to 56, in geologic units that include loess, carbonate bedrock regolith, glacial till and alluvium. Future work in the St. Louis area will focus on the distribution and variation in surficial materials geotechnical properties to improve the reliability of hazard maps.