Integrated Seismic Site Characterization Of The Paducah, Kentucky, Area: Preliminary Results

It is generally accepted that local site geology can play a significant role in the<br>spectral content, amplitudes, and duration of ground motions that are observed as a<br>result of an earthquake. Situated along the lower Ohio river valley are several<br>communities underlain, in part, by poorly consolidated, water saturated sediments. These<br>communities are particularly vulnerable to earthquake damage. One of the largest and<br>most vulnerable cities in the region is Paducah, Kentucky, which is located near the<br>northern extent of the New Madrid seismic zone.<br>Preliminary seismic studies have been performed at several sites in the Paducah area<br>with the intent of determining: 1) the shear wave velocity structure of the thick, poorly<br>consolidated overburden; and 2) depths to bedrock. Conventional P- and SH-wave<br>refraction analysis has given near surface velocities and common-offset reflection profiles<br>have identified shallow subsurface structure. Modified expanding spreads have produced<br>P- and SH-wave top-of-bedrock reflections from depths exceeding 120 m and stacking<br>velocities to major reflectors have been calculated. Downhole seismic data has been<br>used to constrain the velocity models developed using surface seismic methods.<br>From the shear wave velocity and overburden thickness data, site response modeling<br>was performed to determine expected ground motions as a result of an earthquake.