Abstract
As a result of the loss of life and billions of dollars in damage caused by the Armenian (1985), Michoacan (1988), Loma Prieta (1989), and Northridge (1994) earthquakes, increasing emphasis has been given to site effects. Beginning in 1989, Lamont-Doherty Earth Observatory and the University of Kentucky have installed several free-field accelerometers in the vicinity of the New Madrid Seismic Zone that are situated on thick deposits of loose and semi-consolidated sediments characterized by low to moderate shear-wave velocities. Ground motions recorded on these instruments most likely are significantly affected by site effects that are primarily a function of the depth to bedrock, shear-wave velocities, and damping values of the soils. In this study, the depths to the bedrock, near-surface shear-wave velocities, and damping values (for the case of low strains) were determined for 11 of the strong-motion stations along a north-south axis in the New Madrid Seismic Zone by means of conventional P- and SH-wave seismic reflection and refraction techniques.
