Skip Links

USGS - science for a changing world

Open-File Report 2009-1059

In collaboration with the St. Louis Area Earthquake Hazards Mapping Project (SLAEHMP)

St. Louis Area Earthquake Hazards Mapping Project— A Progress Report-November 2008

By D. Karadeniz, J.D. Rogers, R.A. Williams, C.H. Cramer, R.A. Bauer, D. Hoffman, J. Chung, G.L. Hempen, P.J. Steckel, O.L. Boyd, C.M. Watkins, N.S. McCallister, and E. Schweig

Abstract

Thumbnail of cover and link to report PDF (2.1 MB)

Draft probabilistic and deterministic seismic hazard maps for the St. Louis metropolitan area, which include the effects of surficial geology on site response, have been prepared for three pilot USGS 7.5-minute quadrangles of the 29-quadrangle study area. The computer codes used in this study, which are similar to those used in the generation of the USGS national seismic hazard maps, were modified for use in this study by Cramer. These codes, which were implemented by Karadeniz in his Ph.D. thesis on St. Louis area seismic hazards, account for the fully-probabilistic approach in developing the maps and apply the median of site amplification estimates to the hard-rock ground motion attenuation relations in the deterministic maps. All of the seismic hazards were calculated based on a grid of 0.005°, or about every 500 m, the same spacing employed in the amplification distribution calculations. To account for some of the uncertainty found in St. Louis area shear-wave velocity measurements, shear modulus proxies, depth to bedrock calculations, earthquake time histories, and so on, a Monte Carlo randomization procedure was used to generate site-amplification distributions and provide an estimate of the uncertainty, in terms of mean, median, and standard deviation. These distributions were assumed to be lognormal in form.

In this study one-dimensional equivalent-linear response analysis was used to evaluate site-amplifications because of the following reasons: 1) high strain levels are not expected; 2) high excess water pressure development is not expected, and 3) the bedrock structure and overlying soft-sediment layering is near-horizontal in the St. Louis area. When compared to the USGS National Maps, the new probabilistic hazard levels calculated in the pilot study area for upland sites (loess covered residuum, drift, till) show zero to 300 percent greater ground motion levels for peak ground acceleration (PGA), 200 to 250 percent greater ground motion levels for 0.2-s spectral acceleration (SA), and 0 to 175 percent greater ground motion levels for 1.0-s SA. Probabilistic hazard levels for lowland (alluvial) sites, generally the modern Mississippi and Missouri River floodplains, exhibit zero to 200 percent greater ground motion levels for PGA, between 20 percent smaller to 150 percent greater ground motion levels for 0.2-s SA, and 100 to 260 percent greater ground motion levels for 1.0-s SA, when compared to the National Hazard Map.

See Report PDF for full Abstract.

First posted April 13, 2009

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.


Suggested citation:

Karadeniz, D., Rogers, J.D., Williams, R.A., Cramer, C.H., Bauer, R.A., Hoffman, D., Chung, J., Hempen, G.L., Steckel, P.J., Boyd, O.L., Watkins, C.M., McCallister, N.S., and Schweig, E., 2009, St. Louis area earthquake hazards mapping project—A Progress report-November 2008: U.S. Geological Survey Open-File Report 2009-1059, 14 p.



Contents

Executive Summary

Abstract

Introduction

Methodology

Project Accomplishments

Conclusions

References Cited


Accessibility FOIA Privacy Policies and Notices

USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: https://pubs.usgs.gov/of/2009/1059/
Page Contact Information: Contact USGS
Page Last Modified: Wednesday, December 07, 2016, 09:52:19 PM